A355087 E.g.f. A(x) satisfies A(x) = 1 - log(1-x) * A(3*x).
1, 1, 7, 200, 22008, 8968614, 13103201154, 66911528280456, 1170951806182816008, 69148802888161984160496, 13610904625275511792310726256, 8840888240006182011615570947541552, 18793694994107665289261434484161549856688
Offset: 0
Keywords
Programs
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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;
Formula
a(0) = 1; a(n) = Sum_{k=1..n} 3^(n-k) * (k-1)! * binomial(n,k) * a(n-k).