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 A031250 #6 Dec 30 2023 23:01:42 %S A031250 0,0,1,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,1,1,0,0,0,1,1,2,2,3,4,5,4,5, %T A031250 5,4,4,3,3,2,3,2,1,0,0,0,0,0,0,0,0,0,0,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0, %U A031250 1,1,1,0,0,0,0,0,0,0,0,0,0,0,0,1,1,1,0,0,0,0 %N A031250 (# 3's)-(# 4's) in first n terms of A031235. %Y A031250 Cf. A031235. %K A031250 nonn %O A031250 1,28 %A A031250 _Clark Kimberling_