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 A051990 #9 Sep 21 2021 15:45:32 %S A051990 10,15,26,30,35,39,42,65,78,95,105,110,122,143,170,182,195,203,210, %T A051990 222,230,255,290,327,362,395,462,483,485,530,663,885,903,915,930,962, %U A051990 1155,1157,1173,1190,1218,1230,1295,1370,1463,1482,1518,1595 %N A051990 Discriminants of real quadratic fields of ERD-type with class groups of exponent 2 and discriminants of the form D = r^2*k^2+k, k odd. %D A051990 R. A. Mollin, Quadratics, CRC Press, 1996, Appendix A, Table A4(1), column D. %H A051990 Georg Fischer, <a href="/A051990/b051990.txt">Table of n, a(n) for n = 1..98</a> %Y A051990 Cf. A051991, A051992, A051993, A051994, A051995, A051996, A051997, A051998. %K A051990 nonn,fini,full %O A051990 1,1 %A A051990 _N. J. A. Sloane_, Jan 04 2000