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 A099598 #4 Apr 30 2014 01:27:40
%S A099598 1,2,4,8,19,50,162,576,2469,11218,59984,331432,2120663,13784290,
%T A099598 102616622,766648128,6507054537,54919451490,523342287196,
%U A099598 4923469621256,52040350449307,539901936037202,6268123599148282
%N A099598 Antidiagonal sums of array A099597.
%F A099598 a(n)=sum{k=0..n, C(n,k)*(floor(k/2)!)^2}; a(n)=sum{k=0..n, sum{j=0..n-k, C(n-k,j)C(k,j)j!^2}}; - _Paul Barry_, May 26 2007
%K A099598 nonn
%O A099598 0,2
%A A099598 _Ralf Stephan_, Oct 28 2004