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 A307709 #6 Apr 24 2019 00:02:39
%S A307709 0,1,1,2,8,39,240,1726,14189,130790,1334873,14935261,181757070,
%T A307709 2390363103,33787482806,510879775905,8229231626244,140698662551489,
%U A307709 2545031258526411,48561748888174242,974858528384809324,20539450727358618457,453191882910044604304,10450775091071489910630
%N A307709 G.f. A(x) satisfies: A(x) = x*exp(Sum_{n>=1} Sum_{k>=1} (-1)^(k+1)*n*a(n)*x^(n*k)/k).
%F A307709 G.f.: A(x) = Sum_{n>=1} a(n)*x^n = x * Product_{n>=1} (1 + x^n)^(n*a(n)).
%F A307709 Recurrence: a(n+1) = (1/n) * Sum_{k=1..n} ( Sum_{d|k} (-1)^(k/d+1) d^2*a(d) ) * a(n-k+1).
%e A307709 G.f.: A(x) = x + x^2 + 2*x^3 + 8*x^4 + 39*x^5 + 240*x^6 + 1726*x^7 + 14189*x^8 + 130790*x^9 + 1334873*x^10 + ...
%t A307709 a[n_] := a[n] = SeriesCoefficient[x Exp[Sum[Sum[(-1)^(k + 1) 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 A307709 a[n_] := a[n] = SeriesCoefficient[x Product[(1 + x^k)^(k a[k]), {k, 1, n - 1}], {x, 0, n}]; a[1] = 1; Table[a[n], {n, 0, 23}]
%Y A307709 Cf. A004111, A307708.
%K A307709 nonn
%O A307709 0,4
%A A307709 _Ilya Gutkovskiy_, Apr 23 2019