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 A208649 #7 Jun 10 2025 06:02:38
%S A208649 1,1,1,3,6,40,150,2100,14700,423360,5556600,325987200,8068183200,
%T A208649 958961203200,44996257706400,10799101849536000,965169727802280000,
%U A208649 466713183932835840000,79775138681769651120000
%N A208649 (1/n)*A073617(n+1).
%F A208649 a(n) ~ A^(3/2) * 2^((n*(n+3))/4 + 1/3 - (-1)^n/4) * exp(n/4 - 1/8) / (n^(n/4 + 3/2 - (-1)^n/8) * Pi^(n/4 + (5 - (-1)^n)/8)), where A is the Glaisher-Kinkelin constant A074962. - _Vaclav Kotesovec_, Jun 10 2025
%t A208649 p[n_] := Product[Binomial[n + 1 - k, k],
%t A208649 {k, 1, Floor[(n + 1)/2]}]
%t A208649 Table[p[n], {n, 1, 20}] (* A073617(n+1) *)
%t A208649 Table[p[n]/n, {n, 1, 20}] (* A208649 *)
%Y A208649 Cf. A073617.
%K A208649 nonn
%O A208649 1,4
%A A208649 _Clark Kimberling_, Feb 29 2012