cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-4 of 4 results.

A046085 Numbers n such that Q(sqrt(-n)) has class number 4.

Original entry on oeis.org

14, 17, 21, 30, 33, 34, 39, 42, 46, 55, 57, 70, 73, 78, 82, 85, 93, 97, 102, 130, 133, 142, 155, 177, 190, 193, 195, 203, 219, 253, 259, 291, 323, 355, 435, 483, 555, 595, 627, 667, 715, 723, 763, 795, 955, 1003, 1027, 1227, 1243, 1387, 1411, 1435, 1507, 1555
Offset: 1

Views

Author

N. J. A. Sloane, Jun 16 2000

Keywords

Comments

Contains 54 numbers [Arno, Theorem 7], ..., 1387, 1411, 1435, 1507 and 1555. [R. J. Mathar, May 01 2010]

Links

Crossrefs

See A003173, A005847, A006203, A046085, A046002, A055109, A046004, A055110, A046006, A055111 for class numbers 1 through 10.

Programs

A055109 Numbers k such that Q(sqrt(-k)) has class number 6.

Original entry on oeis.org

26, 29, 38, 53, 61, 87, 106, 109, 118, 157, 202, 214, 247, 262, 277, 298, 339, 358, 397, 411, 451, 515, 707, 771, 835, 843, 1059, 1099, 1147, 1203, 1219, 1267, 1315, 1347, 1363, 1563, 1603, 1843, 1915, 1963, 2227, 2283, 2443, 2515, 2563, 2787
Offset: 1

Views

Author

N. J. A. Sloane, Jun 16 2000

Keywords

Links

Crossrefs

See A003173, A005847, A006203, A046085, A046002, A055109, A046004, A055110, A046006, A055111 for class numbers 1 through 10.

Programs

  • Mathematica
    Select[Range[10000], MoebiusMu[#] != 0 && NumberFieldClassNumber[Sqrt[-#]] == 6 &] (* Jinyuan Wang, Mar 08 2020 *)
  • PARI
    \\  See A005847.

A055111 Numbers k such that Q(sqrt(-k)) has class number 10.

Original entry on oeis.org

74, 86, 119, 122, 143, 159, 166, 181, 197, 218, 229, 303, 317, 319, 346, 373, 394, 415, 421, 422, 538, 541, 611, 613, 635, 694, 699, 709, 757, 779, 803, 851, 853, 877, 923, 982, 1093, 1115, 1213, 1318, 1643, 1707, 1779, 1819, 1835, 1891, 1923
Offset: 1

Views

Author

N. J. A. Sloane, Jun 16 2000

Keywords

Links

Crossrefs

See A003173, A005847, A006203, A046085, A046002, A055109, A046004, A055110, A046006, A055111 for class numbers 1 through 10.

Programs

  • Mathematica
    Select[Range[10000], MoebiusMu[#] != 0 && NumberFieldClassNumber[Sqrt[-#]] == 10 &] (* Jinyuan Wang, Mar 08 2020 *)
  • PARI
    \\ See A005847.

A191411 Class number, k, of n; i.e., imaginary quadratic fields negated Q(sqrt(-n))=k, or 0 if n is not squarefree (A005117).

Original entry on oeis.org

1, 1, 1, 0, 2, 2, 1, 0, 0, 2, 1, 0, 2, 4, 2, 0, 4, 0, 1, 0, 4, 2, 3, 0, 0, 6, 0, 0, 6, 4, 3, 0, 4, 4, 2, 0, 2, 6, 4, 0, 8, 4, 1, 0, 0, 4, 5, 0, 0, 0, 2, 0, 6, 0, 4, 0, 4, 2, 3, 0, 6, 8, 0, 0, 8, 8, 1, 0, 8, 4, 7, 0, 4, 10, 0, 0, 8, 4, 5, 0, 0, 4, 3, 0, 4, 10, 6, 0, 12, 0, 2, 0, 4, 8, 8, 0, 4, 0, 0, 0, 14, 4, 5, 0, 8
Offset: 1

Views

Author

Robert G. Wilson v, Jun 01 2011

Keywords

Links

Crossrefs

a(n)= 0: A013929; a(n)= 1: A003173; a(n)= 2: A005847; a(n)= 3: A006203; a(n)= 4: A046085; a(n)= 5: A046002; a(n)= 6: A055109; a(n)= 7: A046004; a(n)= 8: A055110; a(n)= 9: A046006; a(n)=10: A055111; a(n)=11: A046008; a(n)=12: n/a;
a(n)=13: A046010; a(n)=14: n/a; a(n)=15: A046012; a(n)=16: n/a; a(n)=17: A046014; a(n)=18: n/a; a(n)=19: A046016;
a(n)=20: n/a; a(n)=21: A046018; a(n)=22: n/a;
a(n)=23: A046020; a(n)=24: n/a; a(n)=25: A056987; etc.
Cf. A191408, A191410.
Cf. A000924 (without the zeros).

Programs

  • Mathematica
    f[n_] := If[! SquareFreeQ@ n, 0, NumberFieldClassNumber@Sqrt@ -n]; Array[f, 105]
  • PARI
    a(n) = if (! issquarefree(n), 0, qfbclassno(-n*if((-n)%4>1, 4, 1))); \\ Michel Marcus, Jul 08 2015
Showing 1-4 of 4 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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