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 A026902 #5 Mar 30 2012 18:56:11 %S A026902 1,1,4,5,18,24,84,115,400,554,1934,2690,9474,13180,46962,65193,235338, %T A026902 325568,1191292,1641192,6086880,8348342,31369180,42831204,162943236, %U A026902 221515918,852512496,1154208486,4489722568,6055426942 %N A026902 a(n) = T(n,m) + T(n,m+1) + ... + T(n,n), m=[ (n+1)/2 ], T given by A026780. %K A026902 nonn %O A026902 1,3 %A A026902 _Clark Kimberling_