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 A351668 #11 Feb 16 2025 08:34:03 %S A351668 671,815,1007,1844,2036,2071,2191,2264,2319,2599,2708,3188,3223,3284, %T A351668 3439,3991,4087,4276,4696,4835,4859,4979,5579,5912,6107,6459,6463, %U A351668 6488,6535,6635,7087,7115,7303,7576,7835,7971,8259,8267,8367,8483,8948,9019,9076 %N A351668 Discriminants of imaginary quadratic fields with class number 30 (negated). %C A351668 Sequence contains 255 terms; largest is 134467. %C A351668 The class group of Q[sqrt(-d)] is isomorphic to C_30 for all d in this sequence. %H A351668 Andy Huchala, <a href="/A351668/b351668.txt">Table of n, a(n) for n = 1..255</a> %H A351668 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/ClassNumber.html">Class Number</a> %o A351668 (Sage) %o A351668 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 A351668 [-a[0] for a in ls if a[1] == 30] %Y A351668 Cf. A006203, A013658, A014602, A014603, A046002-A046020, A046125, A056987, A351664. %K A351668 nonn,fini,full %O A351668 1,1 %A A351668 _Andy Huchala_, Mar 24 2022