A056987 Discriminants of imaginary quadratic fields with class number 25 (negated).

479, 599, 1367, 2887, 3851, 4787, 5023, 5503, 5843, 7187, 7283, 7307, 7411, 8011, 8179, 9227, 9923, 10099, 11059, 11131, 11243, 11867, 12211, 12379, 12451, 12979, 14011, 14923, 15619, 17483, 18211, 19267, 19699, 19891, 20347, 21107, 21323

Offset: 1

Author

Eric W. Weisstein

Keywords

• nonn
• fini
• full

Comments

Sequence contains 95 members; largest is 93307.

The class group of Q[sqrt(-d)] is isomorphic to C_5 X C_5 for d = 12451 and 37363. For all other d in this sequence, the class group of Q[sqrt(-d)] is isomorphic to C_25. - Jianing Song, Dec 01 2019

Links

• Jianing Song, Table of n, a(n) for n = 1..95
• Eric Weisstein's World of Mathematics, Class Number.

Crossrefs

Cf. A014602, A014603, A006203, A013658, A046002, A046003, A046004, A046005, A046006, A046007, A046008, A046009, A046010, A046011, A046012, A046013, A046014, A046015, A046016, A123563, A046018, A171724, A046020, A048925.

Programs

Mathematica

Reap[ For[n = 1, n < 22000, n++, s = Sqrt[-n]; If[ NumberFieldClassNumber[s] == 25, d = -NumberFieldDiscriminant[s]; Print[d]; Sow[d]]]][[2, 1]] // Union (* Jean-François Alcover, Oct 05 2012 *)