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 A113333 #4 Mar 30 2012 18:36:51
%S A113333 1,1,3,20,217,3206,59000,1288184,32391811,919625298,29062669744,
%T A113333 1011423361344,38432306102230,1583371370586372,70311532983998416,
%U A113333 3348279599587251984,170232740676793931347,9204327574128495048866
%N A113333 Column sums of triangle A113129.
%F A113333 a(k) = Sum_{n=k..2*k} A113129(n, k) for k>=0, where A113129(n, k)=0 for n>=2*k>0.
%Y A113333 Cf. A113129.
%K A113333 nonn
%O A113333 0,3
%A A113333 _Paul D. Hanna_, Nov 03 2005