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 A003647 M0084 #8 Jan 27 2014 08:57:35 %S A003647 1,1,1,2,1,2,1,1,1,2,1,2,2,1,2,2,1,2,1,1,4,1,1,2,2,1,2,4,1,1,2,4,1,2, %T A003647 1,2,1,1,2,4,2,2,2,4,3,1,2,1,2,2,3,2,1,4,1,1,4,1,2,4,2,1,1,6,2,1,2,4, %U A003647 1,1,4,2,1,4,2,4,1,2,1,5,1,2,2,1,4,1,2,4,1,2,1,1,4,6,6,2,2,2,2,2,2,8,1,2,1 %N A003647 Class number of real quadratic forms with discriminant 4n+1. %D A003647 D. A. Buell, Binary Quadratic Forms. Springer-Verlag, NY, 1989, pp. 224-241. %D A003647 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). %Y A003647 Cf. A003648. %K A003647 nonn %O A003647 1,4 %A A003647 _N. J. A. Sloane_, _Mira Bernstein_