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 A051983 #7 Sep 21 2021 07:09:29 %S A051983 519,562,831,879,951,1185,1199,1209,1281,1310,1362,1379,1505,1506, %T A051983 1526,1606,1630,1686,1698,1842,1903,1919,1923,1983,1991,2202,2219, %U A051983 2283,2363,2631,2697,2771,2985,3183,3282,3414,3470,3642,3702,3707 %N A051983 Discriminants of real quadratic fields with class number 2 and related continued fraction period length of 18. %D A051983 R. A. Mollin, Quadratics, CRC Press, 1996, Appendix A, Table A3. %H A051983 Georg Fischer, <a href="/A051983/b051983.txt">Table of n, a(n) for n = 1..187</a> %Y A051983 Cf. A051966-A051989. %K A051983 nonn,fini,full %O A051983 1,1 %A A051983 _N. J. A. Sloane_, Jan 04 2000