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 A129272 #3 Mar 30 2012 18:39:24 %S A129272 0,0,1,0,0,0,0,1,0,0,1,0,0,1,0,0,1,0,1,0,0,1,0,0,1,0,0,1,0,1,0,0,0,0, %T A129272 0,1,0,0,1,0,0,0,0,0,0,0,1,0,1,0,0,0,0,0,0,1,0,0,1,0,1,0,0,1,0,1,0,0, %U A129272 1,0,0,1,0,0,0,0,1,0,0,1,0,0,0,0,0,0,1,0,0,0,0,0,1,0,0,1,0,0,1,0,1,0,0,0,1 %N A129272 a(n)=(1/2)*(2*b(n+1)-3*b(n)+(1-(-1)^b(n))/2) where b(n)=A073941(n). %K A129272 nonn %O A129272 1,1 %A A129272 _Benoit Cloitre_, May 26 2007