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 A218159 #6 Feb 16 2025 08:33:18 %S A218159 1129,3137,4409,5521,6616,6809,7573,7873,10273,10721,11641,12409, %T A218159 12657,13069,14876,15629,16321,17273,17989,18136,18633,19441,21781, %U A218159 22492,22497,23512,24029,24169,24697,24781,25361,26573,27221,27349,28901,29317,31897 %N A218159 Fundamental discriminants of real quadratic number fields with class number 9. %H A218159 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/ClassNumber.html">Class Number</a> %H A218159 <a href="/index/Qua#quadfield">Index entries for sequences related to quadratic fields</a> %t A218159 Select[Range[31897], NumberFieldDiscriminant@Sqrt[#] == # && NumberFieldClassNumber@Sqrt[#] == 9 &] %Y A218159 Cf. A003656, A094619, A094612-A094614, A218156-A218158, A218160. %K A218159 nonn %O A218159 1,1 %A A218159 _Arkadiusz Wesolowski_, Oct 22 2012