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 A163893 #2 Mar 31 2012 13:21:18 %S A163893 2,2,1,19,9,35,8,20,294,146,25,531,1,63,64,334,4688,2223,119,393,8976, %T A163893 547,1064,79832,477,1571,35842,6347,135987,2,7486,140,110337,4211, %U A163893 1195924,249,563,24576,543981,29488,995,30 %N A163893 First differences of A163891. %F A163893 a(n) = A163891(n+1)-A163891(n). %Y A163893 See A163892, A163893. %K A163893 nonn %O A163893 0,1 %A A163893 _Antti Karttunen_, Sep 19 2009