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 A026146 #4 Mar 30 2012 18:56:05 %S A026146 2,2,1,3,2,1,3,2,1,2,1,3,3,2,1,3,2,1,2,1,3,3,2,1,3,2,1,2,1,3,2,1,2,1, %T A026146 3,3,2,1,3,3,2,1,3,2,1,2,1,3,3,2,1,3,2,1,2,1,3,2,1,2,1,3,3,2,1,3,3,2, %U A026146 1,3,2,1,2,1,3,3,2,1,3,2,1,2,1,3,2,1,2,1,3,3,2,1,3,2,1,2,1,3,2 %N A026146 a(n) = (1/2)*|s(n) - s(n-1)|, where s = A026145. %K A026146 nonn %O A026146 3,1 %A A026146 _Clark Kimberling_