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.

Previous Showing 11-19 of 19 results.

A351670 Discriminants of imaginary quadratic fields with class number 32 (negated).

Original entry on oeis.org

791, 1119, 1239, 1463, 1551, 1767, 1784, 1943, 2084, 2180, 2276, 2343, 2840, 2847, 2996, 3080, 3156, 3199, 3207, 3236, 3247, 3295, 3428, 3476, 3679, 3812, 3895, 4088, 4296, 4340, 4495, 4584, 4647, 4767, 4868, 4884, 4964, 4980, 4996, 5012, 5064, 5192, 5215
Offset: 1

Views

Author

Andy Huchala, Mar 24 2022

Keywords

Comments

Sequence contains 708 terms; largest is 164803.
The class groups associated to 187 of the above discriminants are isomorphic to C_32, 273 have a class group isomorphic to C_16 X C_2, 160 isomorphic to C_8 X C_2 X C_2, 60 have a class group isomorphic to C_8 X C_4, 15 have a class group isomorphic to C_4 X C_2 X C_2 X C_2, and the remaining 13 have a class group isomorphic to C_4 X C_4 X C_2.

Links

Crossrefs

Cf. A006203, A013658, A014602, A014603, A046002-A046020, A046125, A056987, A351664.

Programs

  • Sage
    ls = [(QuadraticField(-n, 'a').discriminant(), QuadraticField(-n, 'a').class_number()) for n in (0..10000) if is_fundamental_discriminant(-n) and not is_square(n)];
[-a[0] for a in ls if a[1] == 32]

A351671 Discriminants of imaginary quadratic fields with class number 33 (negated).

Original entry on oeis.org

839, 1583, 1951, 2423, 3967, 4091, 4423, 4567, 4663, 4831, 4999, 5167, 5623, 5791, 6343, 6823, 6967, 7331, 7351, 7499, 8167, 9011, 12619, 13183, 13619, 13931, 14251, 15299, 16619, 17419, 18691, 19163, 21347, 21563, 24019, 25411, 28027, 28163, 28579, 29243
Offset: 1

Views

Author

Andy Huchala, Mar 25 2022

Keywords

Comments

Sequence contains 101 terms; largest is 222643.
The class group of Q[sqrt(-d)] is isomorphic to C_33 for all d in this sequence.

Links

Crossrefs

Cf. A006203, A013658, A014602, A014603, A046002-A046020, A046125, A056987, A351664.

Programs

  • Sage
    ls = [(QuadraticField(-n, 'a').discriminant(), QuadraticField(-n, 'a').class_number()) for n in (0..10000) if is_fundamental_discriminant(-n) and not is_square(n)];
[-a[0] for a in ls if a[1] == 33]

A351673 Discriminants of imaginary quadratic fields with class number 35 (negated).

Original entry on oeis.org

1031, 1223, 2087, 2239, 2543, 4259, 4931, 5171, 5939, 6899, 7211, 7451, 7523, 8219, 8363, 8699, 9007, 9419, 10979, 11411, 11503, 12007, 14939, 15803, 16451, 16651, 17123, 18451, 19259, 20731, 22787, 23011, 24203, 24547, 26387, 26723, 28411, 33619, 36643
Offset: 1

Views

Author

Andy Huchala, Mar 25 2022

Keywords

Comments

Sequence contains 103 terms; largest is 210907.
The class group of Q[sqrt(-d)] is isomorphic to C_35 for all d in this sequence.

Links

Crossrefs

Cf. A006203, A013658, A014602, A014603, A046002-A046020, A046125, A056987, A351664.

Programs

  • Sage
    ls = [(QuadraticField(-n, 'a').discriminant(), QuadraticField(-n, 'a').class_number()) for n in (0..10000) if is_fundamental_discriminant(-n) and not is_square(n)];
[-a[0] for a in ls if a[1] == 35]

A351674 Discriminants of imaginary quadratic fields with class number 36 (negated).

Original entry on oeis.org

959, 1055, 1295, 1599, 1727, 1967, 2199, 2504, 2516, 2895, 3055, 3495, 3656, 3711, 3716, 3896, 3956, 4164, 4255, 4280, 4388, 4472, 4615, 4619, 4623, 4664, 4772, 5007, 5048, 5055, 5063, 5156, 5240, 5291, 5316, 5343, 5455, 5636, 5732, 5767, 5960, 6015, 6055
Offset: 1

Views

Author

Andy Huchala, Mar 27 2022

Keywords

Comments

Sequence contains 668 terms; largest is 217627.
The class groups associated to 255 of the above discriminants are isomorphic to C_36, 374 have a class group isomorphic to C_18 X C_2, 16 have a class group isomorphic to C_12 X C_3, and the remaining 23 have a class group isomorphic to C_6 X C_6.

Links

Crossrefs

Cf. A006203, A013658, A014602, A014603, A046002-A046020, A046125, A056987, A351664-A351680.

Programs

  • Sage
    ls = [(QuadraticField(-n, 'a').discriminant(), QuadraticField(-n, 'a').class_number()) for n in (0..10000) if is_fundamental_discriminant(-n) and not is_square(n)];
[-a[0] for a in ls if a[1] == 36]

A351675 Discriminants of imaginary quadratic fields with class number 37 (negated).

Original entry on oeis.org

1487, 2447, 3391, 5839, 6367, 8147, 9803, 10739, 12343, 12583, 12967, 14767, 15259, 16927, 18947, 19403, 20011, 20147, 21139, 21587, 22807, 23371, 23627, 26731, 28283, 28307, 31699, 31723, 36691, 37171, 37243, 38371, 39139, 39451, 40531, 41659, 42283, 42443
Offset: 1

Views

Author

Andy Huchala, Mar 27 2022

Keywords

Comments

Sequence contains 85 terms; largest is 158923.
The class group of Q[sqrt(-d)] is isomorphic to C_37 for all d in this sequence.

Links

Crossrefs

Cf. A006203, A013658, A014602, A014603, A046002-A046020, A046125, A056987, A351664-A351680.

Programs

  • Sage
    ls = [(QuadraticField(-n, 'a').discriminant(), QuadraticField(-n, 'a').class_number()) for n in (0..10000) if is_fundamental_discriminant(-n) and not is_square(n)];
[-a[0] for a in ls if a[1] == 37]

A351676 Discriminants of imaginary quadratic fields with class number 38 (negated).

Original entry on oeis.org

1199, 1535, 1671, 2031, 3047, 3415, 4916, 5127, 5528, 6423, 6548, 6559, 6927, 7016, 7091, 7135, 7444, 8276, 8315, 8651, 8939, 8983, 9179, 9487, 9524, 9659, 9727, 9908, 10216, 10715, 10779, 10984, 11432, 11463, 11507, 11915, 12779, 12904, 13667, 14099, 14164
Offset: 1

Views

Author

Andy Huchala, Mar 27 2022

Keywords

Comments

Sequence contains 237 terms; largest is 289963.
The class group of Q[sqrt(-d)] is isomorphic to C_38 for all d in this sequence.

Links

Crossrefs

Cf. A006203, A013658, A014602, A014603, A046002-A046020, A046125, A056987, A351664-A351680.

Programs

  • Sage
    ls = [(QuadraticField(-n, 'a').discriminant(), QuadraticField(-n, 'a').class_number()) for n in (0..10000) if is_fundamental_discriminant(-n) and not is_square(n)];
[-a[0] for a in ls if a[1] == 38]

A351677 Discriminants of imaginary quadratic fields with class number 39 (negated).

Original entry on oeis.org

1439, 2207, 2791, 3767, 3919, 4111, 5099, 5119, 6199, 6779, 9059, 9967, 10091, 10163, 10399, 10567, 10667, 11743, 12539, 13163, 13523, 14843, 14867, 15607, 16087, 16139, 16787, 17383, 18127, 21851, 23027, 24499, 26539, 27827, 30211, 30347, 30803, 32027, 32491
Offset: 1

Views

Author

Andy Huchala, Mar 27 2022

Keywords

Comments

Sequence contains 115 terms; largest is 253507.
The class group of Q[sqrt(-d)] is isomorphic to C_39 for all d in this sequence.

Links

Crossrefs

Cf. A006203, A013658, A014602, A014603, A046002-A046020, A046125, A056987, A351664-A351680.

Programs

  • Sage
    ls = [(QuadraticField(-n, 'a').discriminant(), QuadraticField(-n, 'a').class_number()) for n in (0..10000) if is_fundamental_discriminant(-n) and not is_square(n)];
[-a[0] for a in ls if a[1] == 39]

A351678 Discriminants of imaginary quadratic fields with class number 40 (negated).

Original entry on oeis.org

1271, 1839, 2255, 2415, 2559, 2751, 2756, 2919, 2936, 2959, 3044, 3135, 3255, 3399, 3423, 3524, 3704, 3927, 4004, 4047, 4071, 4407, 4607, 4760, 4807, 4820, 4836, 4856, 5060, 5143, 5191, 5304, 5367, 5727, 6020, 6036, 6212, 6324, 6807, 6980, 6996, 7063, 7080
Offset: 1

Views

Author

Andy Huchala, Mar 27 2022

Keywords

Comments

Sequence contains 912 terms; largest is 260947.
The class groups associated to 251 of the above discriminants are isomorphic to C_40, 438 have a class group isomorphic to C_20 X C_2, and the remaining 223 have a class group isomorphic to C_10 X C_2 X C_2.

Links

Crossrefs

Cf. A006203, A013658, A014602, A014603, A046002-A046020, A046125, A056987, A351664-A351680.

Programs

  • Sage
    ls = [(QuadraticField(-n, 'a').discriminant(), QuadraticField(-n, 'a').class_number()) for n in (0..10000) if is_fundamental_discriminant(-n) and not is_square(n)];
[-a[0] for a in ls if a[1] == 40]

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
Previous Showing 11-19 of 19 results.

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