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 A307708 #10 Nov 05 2021 06:04:37
%S A307708 0,1,1,3,12,63,396,2917,24425,228827,2367622,26799874,329366481,
%T A307708 4367857498,62177776756,945859958142,15315466471574,263041021397267,
%U A307708 4776856199304608,91464926203961913,1841802097153485730,38912445829903177835,860714999879617986231,19892998348606063366793
%N A307708 G.f. A(x) satisfies: A(x) = x*exp(Sum_{n>=1} Sum_{k>=1} n*a(n)*x^(n*k)/k).
%H A307708 Vaclav Kotesovec, <a href="/A307708/b307708.txt">Table of n, a(n) for n = 0..440</a>
%F A307708 G.f.: A(x) = Sum_{n>=1} a(n)*x^n = x * Product_{n>=1} 1/(1 - x^n)^(n*a(n)).
%F A307708 Recurrence: a(n+1) = (1/n) * Sum_{k=1..n} ( Sum_{d|k} d^2*a(d) ) * a(n-k+1).
%F A307708 a(n) ~ c * n!, where c = 0.84641771217794232735080969007037092551823744748019035784457815491357287461... - _Vaclav Kotesovec_, Nov 05 2021
%e A307708 G.f.: A(x) = x + x^2 + 3*x^3 + 12*x^4 + 63*x^5 + 396*x^6 + 2917*x^7 + 24425*x^8 + 228827*x^9 + 2367622*x^10 + ...
%t A307708 a[n_] := a[n] = SeriesCoefficient[x Exp[Sum[Sum[j a[j] x^(j k)/k, {k, 1, n - 1}], {j, 1, n - 1}]], {x, 0, n}]; a[1] = 1; Table[a[n], {n, 0, 23}]
%t A307708 a[n_] := a[n] = SeriesCoefficient[x Product[1/(1 - x^k)^(k a[k]), {k, 1, n - 1}], {x, 0, n}]; a[1] = 1; Table[a[n], {n, 0, 23}]
%Y A307708 Cf. A000081, A307709.
%K A307708 nonn
%O A307708 0,4
%A A307708 _Ilya Gutkovskiy_, Apr 23 2019