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 A004196 #10 Jun 11 2014 17:22:16 %S A004196 21,29,35,41,45,49,53,59,61,69,77,83,89,101,115,157 %N A004196 The numbers not expressible as the sum of 4 distinct nonzero squares can be written D*4^n union E. This is E. %H A004196 <a href="/index/Su#ssq">Index entries for sequences related to sums of squares</a> %Y A004196 Cf. A004195, A004441. %K A004196 nonn,fini,full %O A004196 1,1 %A A004196 _N. J. A. Sloane_, _Dan Hoey_