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 A102461 #5 Mar 30 2012 16:50:10 %S A102461 1,2,5,16,56,120 %N A102461 Numbers n such that binomial(n,2) is in A027568. %Y A102461 Cf. A027568. %K A102461 nonn,fini,full %O A102461 1,2 %A A102461 _N. J. A. Sloane_, Sep 06 2008