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 A167687 #2 Mar 30 2012 18:59:26 %S A167687 0,1,0,2,-1,1,0,0,0,1,0,-1,0,0,0,2,-1,0,0,-1,0,0,0,0,0,1,0,0,0,1,0,0, %T A167687 0,0,0,2,-1,0,0,0,0,1,0,0,0,0,0,0,0,1,0,0,0,0,0,-1,0,0,0,0,0,0,0,2,-1, %U A167687 0,0,0,0,0,0,-1,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,2,-1 %N A167687 a(n)=A167683(n)-A167686(n). %K A167687 sign %O A167687 0,4 %A A167687 _Paul Barry_, Nov 09 2009