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 A326860 #6 Jul 27 2019 07:24:13
%S A326860 1,0,2,0,12,48,180,2016,15120,72576,1424304,11249280,113164128,
%T A326860 2066238720,22751977248,303261573888,6400216892160,85934653249536,
%U A326860 1440131337066240,34330891188013056,549029461368181248,11212163885207900160,296439802585781976576
%N A326860 E.g.f.: Product_{k>=1} (1 + x^(3*k-1)/(3*k-1)) / (1 - x^(3*k-1)/(3*k-1)).
%C A326860 In general, if c > 0, mod(d,c) <> 0, mod(d,c) <> 1 and e.g.f. = Product_{k>=1} (1 + x^(c*k+d)/(c*k+d)) / (1 - x^(c*k+d)/(c*k+d)), then a(n) ~ Gamma(1 + (d-1)/c) * n^(2/c - 1) * n! / (c^(2/c) * exp(2*gamma/c) * Gamma(2/c) * Gamma(1 + (d+1)/c)), where gamma is the Euler-Mascheroni constant A001620 and Gamma() is the Gamma function.
%F A326860 a(n) ~ exp(-2*gamma/3) * Gamma(1/3)^2 * n! / (2 * 3^(1/6) * Pi * n^(1/3)), where gamma is the Euler-Mascheroni constant A001620 and Gamma() is the Gamma function.
%t A326860 nmax = 30; CoefficientList[Series[Product[(1+x^(3*k-1)/(3*k-1))/(1-x^(3*k-1)/(3*k-1)), {k, 1, Floor[nmax/3]+1}], {x, 0, nmax}], x] * Range[0, nmax]!
%Y A326860 Cf. A305199, A326755, A326857, A326859, A326861.
%K A326860 nonn
%O A326860 0,3
%A A326860 _Vaclav Kotesovec_, Jul 27 2019