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 A046012 #26 Feb 16 2025 08:32:38 %S A046012 239,439,751,971,1259,1327,1427,1567,1619,2243,2647,2699,2843,3331, %T A046012 3571,3803,4099,4219,5003,5227,5323,5563,5827,5987,6067,6091,6211, %U A046012 6571,7219,7459,7547,8467,8707,8779,9043,9907,10243,10267,10459,10651 %N A046012 Discriminants of imaginary quadratic fields with class number 15 (negated). %C A046012 68 discriminants in this sequence (proved). %H A046012 R. J. Mathar, <a href="/A046012/b046012.txt">Table of n, a(n) for n=1..68</a> (full sequence) %H A046012 Steven Arno, M. L. Robinson, Ferrell S. Wheeler, <a href="http://matwbn.icm.edu.pl/ksiazki/aa/aa83/aa8341.pdf">Imaginary quadratic fields with small odd class number</a>, Acta Arith. 83 (1998) 295-330. %H A046012 Duncan A. Buell, <a href="https://dx.doi.org/10.1090/S0025-5718-1977-0439802-X">Small class numbers and extreme values of L-functions of quadratic fields</a>, Math. Comp., 31 (1977), 786-796. %H A046012 Keith Matthews, <a href="http://www.numbertheory.org/classnos/">Tables of imaginary quadratic fields with small class numbers</a> %H A046012 C. Wagner, <a href="https://dx.doi.org/10.1090/S0025-5718-96-00722-3">Class Number 5, 6 and 7</a>, Math. Comput. 65, 785-800, 1996. %H A046012 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/ClassNumber.html">Class Number.</a> %H A046012 <a href="/index/Qua#quadfield">Index entries for sequences related to quadratic fields</a> %t A046012 Reap[ For[n = 1, n < 12000, n++, s = Sqrt[-n]; If[ NumberFieldClassNumber[s] == 15, d = -NumberFieldDiscriminant[s]; Print[d]; Sow[d]]]][[2, 1]] // Union (* _Jean-François Alcover_, Oct 05 2012 *) %Y A046012 Cf. A006203, A013658, A014602, A014603, A046002-A046020. %K A046012 nonn,fini,full %O A046012 1,1 %A A046012 _Eric W. Weisstein_