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 A107113 #3 Mar 30 2012 18:59:07
%S A107113 1,1,2,3,6,11,24,52,125,307,809,2190,6249,18348,56016,176272,571113,
%T A107113 1906091,6517283,22879944,82144248,301617448,1131401427,4327790902,
%U A107113 16886037207,67073179408,271242546501,1115489848809,4662462489619
%N A107113 Diagonal sums of A107111, viewed as a number triangle.
%F A107113 a(n)=sum{k=0..floor(n/2), sum{j=0..k, binomial((n-2k)(k+1), k-j)*binomial(k+j, j)}/(k+1)}
%K A107113 easy,nonn
%O A107113 0,3
%A A107113 _Paul Barry_, May 12 2005