A386209 G.f. A(x) satisfies A(x) = 1/(1-x)^2 + x^2 * (d/dx A(x)^2).
1, 2, 7, 40, 329, 3474, 44127, 650144, 10862273, 202632498, 4172689415, 94010964072, 2300682029417, 60787775220578, 1725027567563263, 52338601112555648, 1691028812744005697, 57973475215478590626, 2102150579452302435655, 80389277428829219813864
Offset: 0
Keywords
Programs
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PARI
a_vector(n) = my(v=vector(n+1)); for(i=0, n, v[i+1]=i+1+(i-1)*sum(j=0, i-1, v[j+1]*v[i-j])); v;
Formula
a(n) = n + 1 + (n-1) * Sum_{k=0..n-1} a(k) * a(n-1-k).
a(n) = n + 1 + 2 * Sum_{k=0..n-1} k * a(k) * a(n-1-k).