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 A051981 #7 Sep 21 2021 06:57:13 %S A051981 310,391,415,654,655,679,955,1038,1146,1166,1267,1282,1346,1391,1578, %T A051981 1662,1739,1833,1858,1895,1902,2183,2195,2198,2407,2526,2553,2615, %U A051981 3227,3278,3374,3497,3565,3611,3755,3818,3918,4043,4069,4087 %N A051981 Discriminants of real quadratic fields with class number 2 and related continued fraction period length of 16. %D A051981 R. A. Mollin, Quadratics, CRC Press, 1996, Appendix A, Table A3. %H A051981 Georg Fischer, <a href="/A051981/b051981.txt">Table of n, a(n) for n = 1..130</a> %Y A051981 Cf. A051966-A051989. %K A051981 nonn,fini,full %O A051981 1,1 %A A051981 _N. J. A. Sloane_, Jan 04 2000