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 A108663 #3 Mar 30 2012 17:26:17
%S A108663 2,1,3,2,3,1,4,1,1,6,2,1,1,1,3,5,4,1,8,1,1,3,2,1,1,2,2,1,1,1,1,1,1,10,
%T A108663 2,5,1,3,2,2,3,2,2,2,1,5,3,3,1,4,1,1,2,5,3,1,1,3,3,1,4,3,1,4,4,1,1,4,
%U A108663 1,2,1,1,3,1,1,1,2,1,4,6,1,2,2,1,2,1,1,1,2,6,1,1,3,2,4,3,1,3,2,4,3,2,1,1,2
%N A108663 In the decimal expansion of Pi, lengths of sublists with alternative parity.
%C A108663 Take the decimal expansion of Pi: s={3,1,4,1,5,9,2,6,5,3,5,8,9,7,9,3,2,3,8,4,6,2,6,4,3,3,8,3,2,7,9,5,0,2,8,8,4,1,9}. Split s into sublists each with digits of the same parity:{{3,1},{4},{1,5,9},{2,6},{5,3,5},{8},{9,7,9,3},{2},{3},{8,4,6,2,6,4},{3,3},{8},{3}}. The sequence gives the lengths of the sublists: 2,1,3,2,3,1,4,1,1,6,2,1,1,1,3,5,4,1,8.
%t A108663 A108663=Length/@Split[RealDigits[N[Pi, 300]][[1]], Mod[ #1-#2, 2]==0&]
%K A108663 base,nonn
%O A108663 1,1
%A A108663 _Zak Seidov_, Jun 17 2005