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 A107268 #8 Dec 02 2016 22:10:42
%S A107268 1,1,2,5,14,46,173,733,3436,17572,96997,573268,3604687,23990345,
%T A107268 168254444,1238889493,9546211068,76761000444,642524333589,
%U A107268 5586361188966,50351455288661,469653513479395,4526242614854118,45005754238016688
%N A107268 Sums of antidiagonals of A107267.
%H A107268 Alois P. Heinz, <a href="/A107268/b107268.txt">Table of n, a(n) for n = 0..250</a>
%F A107268 a(n) = Sum_{k=0..n} Sum_{j=0..n-k} 1/(j+1) C(j+1,n-k-j+1) C(n-k,j) k^j.
%F A107268 a(n) = Sum_{k=0..n} Sum_{j=0..k} 1/(j+1) C(j+1,k-j+1) C(k,j) (n-k)^j.
%K A107268 easy,nonn
%O A107268 0,3
%A A107268 _Paul Barry_, May 15 2005