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 A110182 #3 Mar 30 2012 18:59:08
%S A110182 1,1,2,2,5,9,26,66,199,575,1790,5542,17945,58733,198880,685296,
%T A110182 2429281,8778321,32491940,122503412,471379771,1844669495,7346727298,
%U A110182 29712688698,122054603983,508548201863,2149211636944,9204566602696,39944636660655
%N A110182 Diagonal sums of number triangle A110180.
%F A110182 a(n)=sum{k=0..floor(n/2), sum{j=0..floor((n-2k)/2), C(n-2k, j)C(n-2k-j, j)k^j}}
%K A110182 easy,nonn
%O A110182 0,3
%A A110182 _Paul Barry_, Jul 14 2005