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 A098696 #11 Jun 29 2019 08:58:09
%S A098696 1,4,104,6544,765344,143639104,39511297664,14979797833984,
%T A098696 7487442077817344,4770988535512474624,3774873839360539879424,
%U A098696 3630982576832133263233024,4172729918808369709126098944
%N A098696 Main diagonal of array in A073146.
%C A098696 Diagonal of Euler-Seidel matrix with start sequence A000670.
%F A098696 a(n) = Sum_{k=0..n} binomial(n, k) * A000670(2*n-k).
%F A098696 a(n) ~ (2*n)! / (sqrt(2) * (log(2))^(2*n+1)). - _Vaclav Kotesovec_, May 03 2015
%F A098696 a(n) = Sum_{k>=0} (k*(k + 1))^n/2^(k+1). - _Ilya Gutkovskiy_, Jun 29 2019
%t A098696 Table[Sum[Binomial[n, k] * Sum[StirlingS2[2*n-k, j]*j!, {j, 0, 2*n-k}],{k,0,n}],{n,0,20}] (* _Vaclav Kotesovec_, May 03 2015 *)
%Y A098696 Cf. A000670, A073146.
%K A098696 nonn
%O A098696 0,2
%A A098696 _Ralf Stephan_, Sep 23 2004
%E A098696 Offset corrected by _Vaclav Kotesovec_, May 03 2015