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 A055220 #4 Mar 30 2012 18:57:04 %S A055220 1,6,28,113,423,1507,5193,17469,57720,188098,606336,1937490,6146895, %T A055220 19386189,60836271,190104957,591899346,1837128933,5686494333, %U A055220 17559366768,54107166250,166412478896,510963917688,1566546588694 %N A055220 T(2n+4,n), array T as in A055216. %K A055220 nonn %O A055220 0,2 %A A055220 _Clark Kimberling_, May 07 2000