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 A190910 #7 Mar 28 2020 06:09:28
%S A190910 1,2,6,23,89,338,1286,4911,18769,71722,273982,1046119,3991913,
%T A190910 15222986,58013678,220939711,840883777,3198349426,12157775958,
%U A190910 46188298519,175376312729,665552754018,2524513742262,9571221986607,36271175050321
%N A190910 a(n) = Sum{0<=k<=n} binomial(n+k,n-k) * k! / (floor(k/2)!)^2.
%C A190910 Row sums of A190909.
%p A190910 A190910 := n -> add(binomial(n+k,n-k)*k!/iquo(k,2)!^2,k=0..n):
%p A190910 seq(A190910(n),n=0..24);
%K A190910 nonn
%O A190910 0,2
%A A190910 _Peter Luschny_, May 24 2011