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 A031233 #4 Mar 30 2012 18:56:21 %S A031233 0,1,0,0,0,0,0,0,0,1,1,0,0,0,1,1,2,2,3,4,5,4,5,5,4,4,3,3,2,3,2,1,0,0, %T A031233 0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,0,0,0,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0,1, %U A031233 1,1,0,0,0,0,0,1,1,1,2,2,2,3,4,4,5,4,4,5,5,5 %N A031233 (# 2's)-(# 3's) in first n terms of A031219. %K A031233 nonn %O A031233 1,17 %A A031233 _Clark Kimberling_