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 A051962 #4 Mar 30 2012 16:48:43 %S A051962 337,569,977,1453,1669,1741,2053,2293,4093,4349,5437,5557,8861,9341, %T A051962 10133,10709,11117,12917,14549,15053,16253,18413,18917,19013,19973, %U A051962 20117,20333,25373,28493,29333 %N A051962 Discriminants of real quadratic fields with class number 1 and related continued fraction period length of 21. %D A051962 R. A. Mollin, Quadratics, CRC Press, 1996, Appendix A. %Y A051962 Cf. A050950-A050969, A051962-A051965. %K A051962 nonn,fini,full %O A051962 1,1 %A A051962 _N. J. A. Sloane_, Jan 04 2000