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.
%I A351669 #10 Feb 16 2025 08:34:03 %S A351669 719,911,2927,3251,3727,3779,4159,4951,5651,6131,6491,7639,8647,9203, %T A351669 10427,11863,12347,12923,13043,13219,13687,14627,14731,15923,17987, %U A351669 18803,19219,20611,24691,24979,28051,32083,32363,35491,38851,39667,39883,41227,41539 %N A351669 Discriminants of imaginary quadratic fields with class number 31 (negated). %C A351669 Sequence contains 73 terms; largest is 133387. %C A351669 The class group of Q[sqrt(-d)] is isomorphic to C_31 for all d in this sequence. %H A351669 Andy Huchala, <a href="/A351669/b351669.txt">Table of n, a(n) for n = 1..73</a> %H A351669 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/ClassNumber.html">Class Number</a> %o A351669 (Sage) %o A351669 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)]; %o A351669 [-a[0] for a in ls if a[1] == 31] %Y A351669 Cf. A006203, A013658, A014602, A014603, A046002-A046020, A046125, A056987, A351664. %K A351669 nonn,fini,full %O A351669 1,1 %A A351669 _Andy Huchala_, Mar 24 2022