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 A351664 #17 Feb 16 2025 08:34:03 %S A351664 551,951,1247,1256,1735,1832,2651,2771,2792,2823,2839,2984,3092,3327, %T A351664 3368,3611,3736,3903,3992,4052,4207,4244,4376,4739,5123,5435,5524, %U A351664 5891,6059,6443,6515,6587,6676,6847,6891,6964,7156,8003,8339,8383,8408,8691,8743 %N A351664 Discriminants of imaginary quadratic fields with class number 26 (negated). %C A351664 Sequence contains 190 terms; largest is 103027. %C A351664 The class group of Q[sqrt(-d)] is isomorphic to C_26 for all d in this sequence. %H A351664 Andy Huchala, <a href="/A351664/b351664.txt">Table of n, a(n) for n = 1..190</a> %H A351664 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/ClassNumber.html">Class Number.</a> %o A351664 (Sage) %o A351664 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 A351664 [-a[0] for a in ls if a[1] == 26] %Y A351664 Cf. A006203, A013658, A014602, A014603, A046002-A046020, A046125, A056987. %K A351664 nonn,fini,full %O A351664 1,1 %A A351664 _Andy Huchala_, Feb 16 2022