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 A111195 #16 Jul 10 2021 06:13:57
%S A111195 1,2,5,26,269,4666,121017,4370722,209364537,12833657010,979336390669,
%T A111195 91018760056938,10120101446389765,1326280083965014634,
%U A111195 202311875122389093761,35535622109342844729074
%N A111195 a(n) = 2^(-n) * Sum_{k=0..n} binomial(2*n+1, 2*k+1) * A000364(k).
%F A111195 a(n) ~ cosh(Pi/2) * 2^(3*n + 3) * n^(2*n + 1/2) / (Pi^(2*n + 1/2) * exp(2*n)). - _Vaclav Kotesovec_, Jul 10 2021
%t A111195 t = Range[0, 34]!CoefficientList[ Series[ Sec[x], {x, 0, 34}], x]; f[n_] := 2^(-n)*Sum [Binomial[2n + 1, 2k + 1]*t[[2k + 1]], {k, 0, n}]; Table[ f[n], {n, 0, 17}] (* _Robert G. Wilson v_, Oct 24 2005 *)
%t A111195 Table[Sum[Binomial[2*n + 1, 2*k + 1]*Abs[EulerE[2*k]], {k, 0, n}] / 2^n, {n, 0, 20}] (* _Vaclav Kotesovec_, Jul 10 2021 *)
%Y A111195 Cf. A000364, A103327, A308715.
%K A111195 easy,nonn
%O A111195 0,2
%A A111195 _Philippe Deléham_, Oct 24 2005
%E A111195 More terms from _Robert G. Wilson v_, Oct 24 2005