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 A308231 #6 May 16 2019 11:54:04
%S A308231 1,1,2,20,1296,811314,6309590183,742323285862918,
%T A308231 1556765505923600080263,67013651952683308325826069725,
%U A308231 67013652019696961835287511727174009053,1738161546565554966558255056834401765693850396861
%N A308231 G.f.: x * Product_{k>=1} (1 + k^k*x^k)^(a(k)/k).
%F A308231 Recurrence: a(n+1) = (1/n) * Sum_{k=1..n} ( Sum_{d|k} (-1)^(k/d+1)*d^k*a(d) ) * a(n-k+1).
%t A308231 a[n_] := a[n] = SeriesCoefficient[x Product[(1 + k^k x^k)^(a[k]/k), {k, 1, n - 1}], {x, 0, n}]; Table[a[n], {n, 1, 12}]
%t A308231 a[n_] := a[n] = Sum[Sum[(-1)^(k/d + 1) d^k a[d], {d, Divisors[k]}] a[n - k], {k, 1, n - 1}]/(n - 1); a[1] = 1; Table[a[n], {n, 1, 12}]
%Y A308231 Cf. A004111, A186633, A308205, A308228.
%K A308231 nonn
%O A308231 1,3
%A A308231 _Ilya Gutkovskiy_, May 16 2019