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 A355087 #7 Jun 18 2022 14:13:57
%S A355087 1,1,7,200,22008,8968614,13103201154,66911528280456,
%T A355087 1170951806182816008,69148802888161984160496,
%U A355087 13610904625275511792310726256,8840888240006182011615570947541552,18793694994107665289261434484161549856688
%N A355087 E.g.f. A(x) satisfies A(x) = 1 - log(1-x) * A(3*x).
%F A355087 a(0) = 1; a(n) = Sum_{k=1..n} 3^(n-k) * (k-1)! * binomial(n,k) * a(n-k).
%o A355087 (PARI) a_vector(n) = my(v=vector(n+1)); v[1]=1; for(i=1, n, v[i+1]=sum(j=1, i, 3^(i-j)*(j-1)!*binomial(i, j)*v[i-j+1])); v;
%Y A355087 Cf. A007840, A355086.
%Y A355087 Cf. A355088.
%K A355087 nonn
%O A355087 0,3
%A A355087 _Seiichi Manyama_, Jun 18 2022