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 A363426 #13 Jun 02 2023 10:19:07
%S A363426 1,1,3,30,840,68934,16821865,12280119400,26868936914550,
%T A363426 176313989066991255,3470564614854890465955,
%U A363426 204936840860491674903711726,36304151491699938200267389259775,19293550877461959142221066537253871070
%N A363426 G.f. satisfies A(x) = exp( Sum_{k>=1} (-1)^(k+1) * A(3*x^k) * x^k/k ).
%H A363426 Seiichi Manyama, <a href="/A363426/b363426.txt">Table of n, a(n) for n = 0..65</a>
%F A363426 A(x) = Sum_{k>=0} a(k) * x^k = Product_{k>=0} (1+x^(k+1))^(3^k * a(k)).
%F A363426 a(0) = 1; a(n) = (1/n) * Sum_{k=1..n} ( Sum_{d|k} (-1)^(k/d+1) * d * 3^(d-1) * a(d-1) ) * a(n-k).
%o A363426 (PARI) seq(n) = my(A=1); for(i=1, n, A=exp(sum(k=1, i, (-1)^(k+1)*subst(A, x, 3*x^k)*x^k/k)+x*O(x^n))); Vec(A);
%Y A363426 Cf. A004111, A363425, A363427.
%Y A363426 Cf. A363338, A363423.
%K A363426 nonn
%O A363426 0,3
%A A363426 _Seiichi Manyama_, Jun 01 2023