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 A051988 #7 Sep 21 2021 07:14:16 %S A051988 586,634,1585,2474,3578,4121,4141,5114,6074,6109,6362,6506,6602,7261, %T A051988 8042,8249,10673,12349,20557,22837,24869,26773,26869,33017,34165, %U A051988 34541,37661,37837,43693,51757,55565,56285,56381,58277,59293 %N A051988 Discriminants of real quadratic fields with class number 2 and related continued fraction period length of 23. %D A051988 R. A. Mollin, Quadratics, CRC Press, 1996, Appendix A, Table A3. %H A051988 Georg Fischer, <a href="/A051988/b051988.txt">Table of n, a(n) for n = 1..59</a> %Y A051988 Cf. A051966-A051989. %K A051988 nonn,fini,full %O A051988 1,1 %A A051988 _N. J. A. Sloane_, Jan 04 2000