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 A026901 #4 Mar 30 2012 18:56:11 %S A026901 1,10,68,396,2136,11062,56070,281306,1406721,7042818,35401568, %T A026901 178975192,910933936,4669860386,24114746282,125416122430,656713729000, %U A026901 3460748531510,18345703137458,97782896293158,523786141723670 %N A026901 T(2n+1,n+4), T given by A026780. %K A026901 nonn %O A026901 3,2 %A A026901 _Clark Kimberling_