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 A196923 #25 Oct 11 2017 09:07:56 %S A196923 3,4,7,8,11,15,19,20,24,35,40,43,51,52,67,88,91,115,123,148,163,187, %T A196923 232,267,403,427 %N A196923 Values of fundamental discriminant -d where number of ideal classes Q(sqrt(-d)) is at most two. %C A196923 Equals A014602 union A014603. - _Michel Marcus_, Nov 02 2013 %H A196923 A. Schinzel, <a href="http://journals.impan.gov.pl/ba/Inf/59-2-2.html">Solution to a Problem of Lubelski and an Improvement of a Theorem of His</a>, Bull. Pol. Acad. Sci. Math. Vol. 59 No 2 2011 pp. 115-119. %H A196923 H. M. Stark, <a href="http://www.jstor.org/stable/2005481">On complex quadratic fields with class number two</a>, Math. Comp. 29, 1975, pp. 289-302. %K A196923 nonn,fini,full %O A196923 1,1 %A A196923 _Artur Jasinski_, Oct 07 2011