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 A326859 #5 Jul 27 2019 07:23:46
%S A326859 1,2,4,16,80,448,3136,24512,218368,2169600,23752704,282882048,
%T A326859 3661787136,51076644864,763127316480,12184024793088,206679198990336,
%U A326859 3710945850949632,70379726872117248,1405297582300200960,29462283451103182848,647386758393297371136
%N A326859 E.g.f.: Product_{k>=1} (1 + x^(2*k-1)/(2*k-1)) / (1 - x^(2*k-1)/(2*k-1)).
%F A326859 a(n) ~ exp(-gamma) * n * n!, where gamma is the Euler-Mascheroni constant A001620.
%t A326859 nmax = 25; CoefficientList[Series[Product[(1+x^(2*k-1)/(2*k-1))/(1-x^(2*k-1)/(2*k-1)), {k, 1, Floor[nmax/2]+1}], {x, 0, nmax}], x] * Range[0, nmax]!
%Y A326859 Cf. A088994, A294506, A305199.
%K A326859 nonn
%O A326859 0,2
%A A326859 _Vaclav Kotesovec_, Jul 27 2019