600 (number)

From HandWiki
Short description: Natural number
← 599 600 601 →
Cardinalsix hundred
Ordinal600th
(six hundredth)
Factorization23 × 3 × 52
Divisors1, 2, 3, 4, 5, 6, 8, 10, 12, 15, 20, 24, 25, 30, 40, 50, 60, 75, 100, 120, 150, 200, 300, 600
Greek numeralΧ´
Roman numeralDC
Binary10010110002
Ternary2110203
Quaternary211204
Quinary44005
Senary24406
Octal11308
Duodecimal42012
Hexadecimal25816
Vigesimal1A020
Base 36GO36

600 (six hundred) is the natural number following 599 and preceding 601.

Mathematical properties

Six hundred is a composite number, an abundant number, a pronic number[1] and a Harshad number.

Credit and cars

  • In the United States, a credit score of 600 or below is considered poor, limiting available credit at a normal interest rate.
  • NASCAR runs 600 advertised miles in the Coca-Cola 600, its longest race.
  • The Fiat 600 is a car, the SEAT 600 its Spanish version.

Integers from 601 to 699

600s

610s

Main page: 613 (number)
  • 613 = prime number, first number of prime triple (p, p + 4, p + 6), middle number of sexy prime triple (p − 6, p, p + 6). Geometrical numbers: Centered square number with 18 per side, circular number of 21 with a square grid and 27 using a triangular grid. Also 17-gonal. Hypotenuse of a right triangle with integral sides, these being 35 and 612. Partitioning: 613 partitions of 47 into non-factor primes, 613 non-squashing partitions into distinct parts of the number 54. Squares: Sum of squares of two consecutive integers, 17 and 18. Additional properties: a lucky number, index of prime Lucas number.[9]
    • In Judaism the number 613 is very significant, as its metaphysics, the Kabbalah, views every complete entity as divisible into 613 parts: 613 parts of every Sefirah; 613 mitzvot, or divine Commandments in the Torah; 613 parts of the human body.
    • The number 613 hangs from the rafters at Madison Square Garden in honor of New York Knicks coach Red Holzman's 613 victories.
  • 614 = 2 × 307, nontotient, 2-Knödel number. According to Rabbi Emil Fackenheim, the number of Commandments in Judaism should be 614 rather than the traditional 613.
  • 615 = 3 × 5 × 41, sphenic number
Main page: 616 (number)
  • 616 = 23 × 7 × 11, Padovan number, balanced number,[10] an alternative value for the Number of the Beast (more commonly accepted to be 666).
  • 617 = prime number, sum of five consecutive primes (109 + 113 + 127 + 131 + 137), Chen prime, Eisenstein prime with no imaginary part, number of compositions of 17 into distinct parts,[11] prime index prime, index of prime Lucas number[9]
    • Area code 617, a telephone area code covering the metropolitan Boston area.
  • 618 = 2 × 3 × 103, sphenic number, admirable number.
  • 619 = prime number, strobogrammatic prime,[12] alternating factorial[13]

620s

  • 620 = 22 × 5 × 31, sum of four consecutive primes (149 + 151 + 157 + 163), sum of eight consecutive primes (61 + 67 + 71 + 73 + 79 + 83 + 89 + 97). The sum of the first 620 primes is itself prime.[14]
  • 621 = 33 × 23, Harshad number, the discriminant of a totally real cubic field[15]
  • 622 = 2 × 311, nontotient, Fine number. Fine's sequence (or Fine numbers): number of relations of valence >= 1 on an n-set; also number of ordered rooted trees with n edges having root of even degree It is also the standard diameter of modern road bicycle wheels (622 mm, from hook bead to hook bead)
  • 623 = 7 × 89, number of partitions of 23 into an even number of parts[16]
  • 624 = 24 × 3 × 13 = J4(5),[17] sum of a twin prime (311 + 313), Harshad number, Zuckerman number
  • 625 = 252 = 54, sum of seven consecutive primes (73 + 79 + 83 + 89 + 97 + 101 + 103), centered octagonal number,[18] 1-automorphic number, Friedman number since 625 = 56−2[19]
  • 626 = 2 × 313, nontotient, 2-Knödel number. Stitch's experiment number.
  • 627 = 3 × 11 × 19, sphenic number, number of integer partitions of 20,[20] Smith number[21]
  • 628 = 22 × 157, nontotient, totient sum for first 45 integers
  • 629 = 17 × 37, highly cototient number,[22] Harshad number, number of diagonals in a 37-gon[23]

630s

  • 630 = 2 × 32 × 5 × 7, sum of six consecutive primes (97 + 101 + 103 + 107 + 109 + 113), triangular number, hexagonal number,[24] sparsely totient number,[25] Harshad number, balanced number[26]
  • 631 = Cuban prime number, centered triangular number,[27] centered hexagonal number,[28] Chen prime, lazy caterer number (sequence A000124 in the OEIS)
  • 632 = 23 × 79, number of 13-bead necklaces with 2 colors[29]
  • 633 = 3 × 211, sum of three consecutive primes (199 + 211 + 223), Blum integer; also, in the title of the movie 633 Squadron
  • 634 = 2 × 317, nontotient, Smith number[21]
  • 635 = 5 × 127, sum of nine consecutive primes (53 + 59 + 61 + 67 + 71 + 73 + 79 + 83 + 89), Mertens function(635) = 0, number of compositions of 13 into pairwise relatively prime parts[30]
    • "Project 635", the Irtysh River diversion project in China involving a dam and a canal.
  • 636 = 22 × 3 × 53, sum of ten consecutive primes (43 + 47 + 53 + 59 + 61 + 67 + 71 + 73 + 79 + 83), Smith number,[21] Mertens function(636) = 0
  • 637 = 72 × 13, Mertens function(637) = 0, decagonal number[31]
  • 638 = 2 × 11 × 29, sphenic number, sum of four consecutive primes (151 + 157 + 163 + 167), nontotient, centered heptagonal number[32]
  • 639 = 32 × 71, sum of the first twenty primes, also ISO 639 is the ISO's standard for codes for the representation of languages

640s

  • 640 = 27 × 5, Harshad number, hexadecagonal number,[33] number of 1's in all partitions of 24 into odd parts,[34] number of acres in a square mile
  • 641 = prime number, Sophie Germain prime,[35] factor of 4294967297 (the smallest nonprime Fermat number), Chen prime, Eisenstein prime with no imaginary part, Proth prime[36]
  • 642 = 2 × 3 × 107 = 14 + 24 + 54,[37] sphenic number, admirable number
  • 643 = prime number, largest prime factor of 123456
  • 644 = 22 × 7 × 23, nontotient, Perrin number,[38] Harshad number, common umask, admirable number
  • 645 = 3 × 5 × 43, sphenic number, octagonal number, Smith number,[21] Fermat pseudoprime to base 2,[39] Harshad number
  • 646 = 2 × 17 × 19, sphenic number, also ISO 646 is the ISO's standard for international 7-bit variants of ASCII, number of permutations of length 7 without rising or falling successions[40]
  • 647 = prime number, sum of five consecutive primes (113 + 127 + 131 + 137 + 139), Chen prime, Eisenstein prime with no imaginary part, 3647 - 2647 is prime[41]
  • 648 = 23 × 34 = A331452(7, 1),[42] Harshad number, Achilles number, area of a square with diagonal 36[43]
  • 649 = 11 × 59, Blum integer

650s

  • 650 = 2 × 52 × 13, primitive abundant number,[44] square pyramidal number,[45] pronic number,[1] nontotient, totient sum for first 46 integers; (other fields) the number of seats in the House of Commons of the United Kingdom, admirable number
  • 651 = 3 × 7 × 31, sphenic number, pentagonal number,[46] nonagonal number[47]
  • 652 = 22 × 163, maximal number of regions by drawing 26 circles[48]
  • 653 = prime number, Sophie Germain prime,[35] balanced prime,[3] Chen prime, Eisenstein prime with no imaginary part
  • 654 = 2 × 3 × 109, sphenic number, nontotient, Smith number,[21] admirable number
  • 655 = 5 × 131, number of toothpicks after 20 stages in a three-dimensional grid[49]
  • 656 = 24 × 41 = [math]\displaystyle{ \lfloor \frac{3^{16}}{2^{16}} \rfloor }[/math].[50] In Judaism, 656 is the number of times that Jerusalem is mentioned in the Hebrew Bible or Old Testament.
  • 657 = 32 × 73, the largest known number not of the form a2+s with s a semiprime
  • 658 = 2 × 7 × 47, sphenic number, untouchable number
  • 659 = prime number, Sophie Germain prime,[35] sum of seven consecutive primes (79 + 83 + 89 + 97 + 101 + 103 + 107), Chen prime, Mertens function sets new low of −10 which stands until 661, highly cototient number,[22] Eisenstein prime with no imaginary part, strictly non-palindromic number[4]

660s

  • 660 = 22 × 3 × 5 × 11
    • Sum of four consecutive primes (157 + 163 + 167 + 173).
    • Sum of six consecutive primes (101 + 103 + 107 + 109 + 113 + 127).
    • Sum of eight consecutive primes (67 + 71 + 73 + 79 + 83 + 89 + 97 + 101).
    • Sparsely totient number.[25]
    • Sum of 11th row when writing the natural numbers as a triangle.[51]
    • Harshad number.
  • 661 = prime number
    • Sum of three consecutive primes (211 + 223 + 227).
    • Mertens function sets new low of −11 which stands until 665.
    • Pentagram number of the form [math]\displaystyle{ 5n^{2}-5n+1 }[/math].
    • Hexagram number of the form [math]\displaystyle{ 6n^{2}-6n+1 }[/math] i.e. a star number.
  • 662 = 2 × 331, nontotient, member of Mian–Chowla sequence[52]
  • 663 = 3 × 13 × 17, sphenic number, Smith number[21]
  • 664 = 23 × 83, number of knapsack partitions of 33[53]
    • Telephone area code for Montserrat.
    • Area code for Tijuana within Mexico.
    • Model number for the Amstrad CPC664 home computer.
  • 665 = 5 × 7 × 19, sphenic number, Mertens function sets new low of −12 which stands until 1105, number of diagonals in a 38-gon[23]
  • 666 = 2 × 32 × 37, repdigit
  • 667 = 23 × 29, lazy caterer number (sequence A000124 in the OEIS)
  • 668 = 22 × 167, nontotient
  • 669 = 3 × 223, blum integer

670s

  • 670 = 2 × 5 × 67, sphenic number, octahedral number,[54] nontotient
  • 671 = 11 × 61. This number is the magic constant of n×n normal magic square and n-queens problem for n = 11.
  • 672 = 25 × 3 × 7, harmonic divisor number,[55] Zuckerman number, admirable number
  • 673 = prime number, Proth prime[36]
  • 674 = 2 × 337, nontotient, 2-Knödel number
  • 675 = 33 × 52, Achilles number
  • 676 = 22 × 132 = 262, palindromic square
  • 677 = prime number, Chen prime, Eisenstein prime with no imaginary part, number of non-isomorphic self-dual multiset partitions of weight 10[56]
  • 678 = 2 × 3 × 113, sphenic number, nontotient, number of surface points of an octahedron with side length 13,[57] admirable number
  • 679 = 7 × 97, sum of three consecutive primes (223 + 227 + 229), sum of nine consecutive primes (59 + 61 + 67 + 71 + 73 + 79 + 83 + 89 + 97), smallest number of multiplicative persistence 5[58]

680s

  • 680 = 23 × 5 × 17, tetrahedral number,[59] nontotient
  • 681 = 3 × 227, centered pentagonal number[2]
  • 682 = 2 × 11 × 31, sphenic number, sum of four consecutive primes (163 + 167 + 173 + 179), sum of ten consecutive primes (47 + 53 + 59 + 61 + 67 + 71 + 73 + 79 + 83 + 89), number of moves to solve the Norwegian puzzle strikketoy.[60]
  • 683 = prime number, Sophie Germain prime,[35] sum of five consecutive primes (127 + 131 + 137 + 139 + 149), Chen prime, Eisenstein prime with no imaginary part, Wagstaff prime[61]
  • 684 = 22 × 32 × 19, Harshad number, number of graphical forest partitions of 32[62]
  • 685 = 5 × 137, centered square number[63]
  • 686 = 2 × 73, nontotient, number of multigraphs on infinite set of nodes with 7 edges[64]
  • 687 = 3 × 229, 687 days to orbit the sun (Mars) D-number[65]
  • 688 = 24 × 43, Friedman number since 688 = 8 × 86,[19] 2-automorphic number[66]
  • 689 = 13 × 53, sum of three consecutive primes (227 + 229 + 233), sum of seven consecutive primes (83 + 89 + 97 + 101 + 103 + 107 + 109). Strobogrammatic number[67]

690s

  • 690 = 2 × 3 × 5 × 23, sum of six consecutive primes (103 + 107 + 109 + 113 + 127 + 131), sparsely totient number,[25] Smith number,[21] Harshad number
    • ISO 690 is the ISO's standard for bibliographic references
  • 691 = prime number, (negative) numerator of the Bernoulli number B12 = -691/2730. Ramanujan's tau function τ and the divisor function σ11 are related by the remarkable congruence τ(n) ≡ σ11(n) (mod 691).
    • In number theory, 691 is a "marker" (similar to the radioactive markers in biology): whenever it appears in a computation, one can be sure that Bernoulli numbers are involved.
  • 692 = 22 × 173, number of partitions of 48 into powers of 2[68]
  • 693 = 32 × 7 × 11, triangular matchstick number,[69] the number of the "non-existing" Alabama State Constitution amendment, the number of sections in Ludwig Wittgenstein's Philosophical Investigations.
  • 694 = 2 × 347, centered triangular number,[27] nontotient
  • 695 = 5 × 139, 695!! + 2 is prime.[70]
  • 696 = 23 × 3 × 29, sum of eight consecutive primes (71 + 73 + 79 + 83 + 89 + 97 + 101 + 103), totient sum for first 47 integers, trails of length 9 on honeycomb lattice [71]
  • 697 = 17 × 41, cake number; the number of sides of Colorado[72]
  • 698 = 2 × 349, nontotient, sum of squares of two primes[73]
  • 699 = 3 × 233, D-number[65]

References

  1. 1.0 1.1 "Sloane's A002378 : Oblong (or promic, pronic, or heteromecic) numbers". OEIS Foundation. https://oeis.org/A002378. 
  2. 2.0 2.1 "Sloane's A005891 : Centered pentagonal numbers". OEIS Foundation. https://oeis.org/A005891. 
  3. 3.0 3.1 "Sloane's A006562 : Balanced primes". OEIS Foundation. https://oeis.org/A006562. 
  4. 4.0 4.1 "Sloane's A016038 : Strictly non-palindromic numbers". OEIS Foundation. https://oeis.org/A016038. 
  5. Sloane, N. J. A., ed. "Sequence A331452". OEIS Foundation. https://oeis.org/A331452. Retrieved 2022-05-09. 
  6. Sloane, N. J. A., ed. "Sequence A000787 (Strobogrammatic numbers)". OEIS Foundation. https://oeis.org/A000787. Retrieved 2022-05-07. 
  7. "Sloane's A000045 : Fibonacci numbers". OEIS Foundation. https://oeis.org/A000045. 
  8. "Sloane's A002559 : Markoff (or Markov) numbers". OEIS Foundation. https://oeis.org/A002559. 
  9. 9.0 9.1 Sloane, N. J. A., ed. "Sequence A001606 (Indices of prime Lucas numbers)". OEIS Foundation. https://oeis.org/A001606. 
  10. Sloane, N. J. A., ed. "Sequence A020492 (Balanced numbers: numbers k such that phi(k) (A000010) divides sigma(k) (A000203))". OEIS Foundation. https://oeis.org/A020492. 
  11. Sloane, N. J. A., ed. "Sequence A032020 (Number of compositions (ordered partitions) of n into distinct parts)". OEIS Foundation. https://oeis.org/A032020. Retrieved 2022-05-24. 
  12. "Sloane's A007597 : Strobogrammatic primes". OEIS Foundation. https://oeis.org/A007597. 
  13. "Sloane's A005165 : Alternating factorials". OEIS Foundation. https://oeis.org/A005165. 
  14. OEISA013916
  15. Sloane, N. J. A., ed. "Sequence A006832 (Discriminants of totally real cubic fields)". OEIS Foundation. https://oeis.org/A006832. Retrieved 2022-05-31. 
  16. Sloane, N. J. A., ed. "Sequence A027187 (Number of partitions of n into an even number of parts)". OEIS Foundation. https://oeis.org/A027187. Retrieved 2022-05-31. 
  17. Sloane, N. J. A., ed. "Sequence A059377 (Jordan function J_4(n))". OEIS Foundation. https://oeis.org/A059377. Retrieved 2022-05-24. 
  18. "Sloane's A016754 : Odd squares: a(n) = (2n+1)^2. Also centered octagonal numbers". OEIS Foundation. https://oeis.org/A016754. 
  19. 19.0 19.1 "Sloane's A036057 : Friedman numbers". OEIS Foundation. https://oeis.org/A036057. 
  20. "Sloane's A000041 : a(n) = number of partitions of n". OEIS Foundation. https://oeis.org/A000041. 
  21. 21.0 21.1 21.2 21.3 21.4 21.5 21.6 "Sloane's A006753 : Smith numbers". OEIS Foundation. https://oeis.org/A006753. 
  22. 22.0 22.1 "Sloane's A100827 : Highly cototient numbers". OEIS Foundation. https://oeis.org/A100827. 
  23. 23.0 23.1 Sloane, N. J. A., ed. "Sequence A000096 (a(n) = n*(n+3)/2)". OEIS Foundation. https://oeis.org/A000096. Retrieved 2022-05-31. 
  24. "Sloane's A000384 : Hexagonal numbers". OEIS Foundation. https://oeis.org/A000384. 
  25. 25.0 25.1 25.2 "Sloane's A036913 : Sparsely totient numbers". OEIS Foundation. https://oeis.org/A036913. 
  26. Sloane, N. J. A., ed. "Sequence A020492 (Balanced numbers: numbers k such that phi(k) (A000010) divides sigma(k) (A000203))". OEIS Foundation. https://oeis.org/A020492. 
  27. 27.0 27.1 "Sloane's A005448 : Centered triangular numbers". OEIS Foundation. https://oeis.org/A005448. 
  28. "Sloane's A003215 : Hex (or centered hexagonal) numbers". OEIS Foundation. https://oeis.org/A003215. 
  29. Sloane, N. J. A., ed. "Sequence A000031 (Number of n-bead necklaces with 2 colors when turning over is not allowed; also number of output sequences from a simple n-stage cycling shift register; also number of binary irreducible polynomials whose degree divides n)". OEIS Foundation. https://oeis.org/A000031. Retrieved 2022-05-31. 
  30. Sloane, N. J. A., ed. "Sequence A101268 (Number of compositions of n into pairwise relatively prime parts)". OEIS Foundation. https://oeis.org/A101268. Retrieved 2022-05-31. 
  31. "Sloane's A001107 : 10-gonal (or decagonal) numbers". OEIS Foundation. https://oeis.org/A001107. 
  32. "Sloane's A069099 : Centered heptagonal numbers". OEIS Foundation. https://oeis.org/A069099. 
  33. Sloane, N. J. A., ed. "Sequence A051868 (16-gonal (or hexadecagonal) numbers: a(n) = n*(7*n-6))". OEIS Foundation. https://oeis.org/A051868. Retrieved 2022-05-31. 
  34. Sloane, N. J. A., ed. "Sequence A036469 (Partial sums of A000009 (partitions into distinct parts))". OEIS Foundation. https://oeis.org/A036469. 
  35. 35.0 35.1 35.2 35.3 "Sloane's A005384 : Sophie Germain primes". OEIS Foundation. https://oeis.org/A005384. 
  36. 36.0 36.1 "Sloane's A080076 : Proth primes". OEIS Foundation. https://oeis.org/A080076. 
  37. Sloane, N. J. A., ed. "Sequence A074501 (a(n) = 1^n + 2^n + 5^n)". OEIS Foundation. https://oeis.org/A074501. Retrieved 2022-05-31. 
  38. "Sloane's A001608 : Perrin sequence". OEIS Foundation. https://oeis.org/A001608. 
  39. "Sloane's A001567 : Fermat pseudoprimes to base 2". OEIS Foundation. https://oeis.org/A001567. 
  40. Sloane, N. J. A., ed. "Sequence A002464 (Hertzsprung's problem: ways to arrange n non-attacking kings on an n X n board, with 1 in each row and column. Also number of permutations of length n without rising or falling successions)". OEIS Foundation. https://oeis.org/A002464. Retrieved 2022-05-31. 
  41. Sloane, N. J. A., ed. "Sequence A057468 (Numbers k such that 3^k - 2^k is prime)". OEIS Foundation. https://oeis.org/A057468. Retrieved 2022-05-31. 
  42. "Sloane's A331452". OEIS Foundation. https://oeis.org/A331452. 
  43. Sloane, N. J. A., ed. "Sequence A001105 (a(n) = 2*n^2)". OEIS Foundation. https://oeis.org/A001105. 
  44. "Sloane's A071395 : Primitive abundant numbers". OEIS Foundation. https://oeis.org/A071395. 
  45. "Sloane's A000330 : Square pyramidal numbers". OEIS Foundation. https://oeis.org/A000330. 
  46. "Sloane's A000326 : Pentagonal numbers". OEIS Foundation. https://oeis.org/A000326. 
  47. "Sloane's A001106 : 9-gonal (or enneagonal or nonagonal) numbers". OEIS Foundation. https://oeis.org/A001106. 
  48. Sloane, N. J. A., ed. "Sequence A014206 (a(n) = n^2 + n + 2)". OEIS Foundation. https://oeis.org/A014206. Retrieved 2022-05-31. 
  49. Sloane, N. J. A., ed. "Sequence A160160 (Toothpick sequence in the three-dimensional grid)". OEIS Foundation. https://oeis.org/A160160. Retrieved 2022-05-31. 
  50. Sloane, N. J. A., ed. "Sequence A002379 (a(n) = floor(3^n / 2^n))". OEIS Foundation. https://oeis.org/A002379. Retrieved 2022-05-31. 
  51. Sloane, N. J. A., ed. "Sequence A027480 (a(n) = n*(n+1)*(n+2)/2)". OEIS Foundation. https://oeis.org/A027480. Retrieved 2022-05-31. 
  52. "Sloane's A005282 : Mian-Chowla sequence". OEIS Foundation. https://oeis.org/A005282. 
  53. Sloane, N. J. A., ed. "Sequence A108917 (Number of knapsack partitions of n)". OEIS Foundation. https://oeis.org/A108917. Retrieved 2022-05-31. 
  54. "Sloane's A005900 : Octahedral numbers". OEIS Foundation. https://oeis.org/A005900. 
  55. "Sloane's A001599 : Harmonic or Ore numbers". OEIS Foundation. https://oeis.org/A001599. 
  56. Sloane, N. J. A., ed. "Sequence A316983 (Number of non-isomorphic self-dual multiset partitions of weight n)". OEIS Foundation. https://oeis.org/A316983. Retrieved 2022-05-31. 
  57. Sloane, N. J. A., ed. "Sequence A005899 (Number of points on surface of octahedron with side n)". OEIS Foundation. https://oeis.org/A005899. Retrieved 2022-05-31. 
  58. Sloane, N. J. A., ed. "Sequence A003001 (Smallest number of multiplicative persistence n)". OEIS Foundation. https://oeis.org/A003001. Retrieved 2022-05-31. 
  59. "Sloane's A000292 : Tetrahedral numbers". OEIS Foundation. https://oeis.org/A000292. 
  60. Sloane, N. J. A., ed. "Sequence A000975 (Lichtenberg sequence)". OEIS Foundation. https://oeis.org/A000975. Retrieved 2022-05-31. 
  61. "Sloane's A000979 : Wagstaff primes". OEIS Foundation. https://oeis.org/A000979. 
  62. Sloane, N. J. A., ed. "Sequence A000070 (a(n) = Sum_{k=0..n} p(k) where p(k) = number of partitions of k (A000041))". OEIS Foundation. https://oeis.org/A000070. Retrieved 2022-05-31. 
  63. "Sloane's A001844 : Centered square numbers". OEIS Foundation. https://oeis.org/A001844. 
  64. Sloane, N. J. A., ed. "Sequence A050535 (Number of multigraphs on infinite set of nodes with n edges)". OEIS Foundation. https://oeis.org/A050535. Retrieved 2022-05-31. 
  65. 65.0 65.1 Sloane, N. J. A., ed. "Sequence A033553 (3-Knödel numbers or D-numbers: numbers n > 3 such that n divides k^(n-2)-k for all k with gcd(k, n) = 1)". OEIS Foundation. https://oeis.org/A033553. Retrieved 2022-05-31. 
  66. Sloane, N. J. A., ed. "Sequence A030984 (2-automorphic numbers)". OEIS Foundation. https://oeis.org/A030984. Retrieved 2021-09-01. 
  67. "Sloane's A000787 : Strobogrammatic numbers". OEIS Foundation. https://oeis.org/A000787. 
  68. Sloane, N. J. A., ed. "Sequence A000123 (Number of binary partitions: number of partitions of 2n into powers of 2)". OEIS Foundation. https://oeis.org/A000123. Retrieved 2022-05-31. 
  69. Sloane, N. J. A., ed. "Sequence A045943 (Triangular matchstick numbers: a(n) = 3*n*(n+1)/2)". OEIS Foundation. https://oeis.org/A045943. Retrieved 2022-05-31. 
  70. Sloane, N. J. A., ed. "Sequence A076185 (Numbers n such that n!! + 2 is prime)". OEIS Foundation. https://oeis.org/A076185. Retrieved 2022-05-31. 
  71. Sloane, N. J. A., ed. "Sequence A006851 (Trails of length n on honeycomb lattice)". OEIS Foundation. https://oeis.org/A006851. Retrieved 2022-05-18. 
  72. "Colorado is a rectangle? Think again". https://bigthink.com/strange-maps/colorado-is-not-a-rectangle. 
  73. Sloane, N. J. A., ed. "Sequence A045636 (Numbers of the form p^2 + q^2, with p and q primes)". OEIS Foundation. https://oeis.org/A045636. Retrieved 2022-05-31.