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 A031234 #4 Mar 30 2012 18:56:21 %S A031234 0,0,1,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,1,1,0,1,1,2,2,3,3,4,5,6,5, %T A031234 4,4,3,3,2,2,1,2,1,0,0,0,0,0,0,0,0,0,0,0,0,1,1,1,0,0,0,0,0,0,0,0,0,0, %U A031234 0,0,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0,1,1,1,0,0 %N A031234 (# 3's)-(# 4's) in first n terms of A031219. %K A031234 nonn %O A031234 1,27 %A A031234 _Clark Kimberling_