A355494 Expansion of Sum_{k>=0} (k * x/(1 - x))^k.
1, 1, 5, 36, 350, 4328, 65132, 1155904, 23640724, 547544032, 14166236708, 404944248104, 12674392793900, 431104742439088, 15834117059443828, 624575921756875960, 26332801242942780668, 1181750740315156943936, 56244454481507648435012
Offset: 0
Keywords
Links
- Winston de Greef, Table of n, a(n) for n = 0..385
Programs
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Mathematica
Join[{1}, Table[Sum[k^k * Binomial[n-1,k-1], {k,1,n}], {n, 1, 20}]] (* Vaclav Kotesovec, Jul 05 2022 *)
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PARI
my(N=20, x='x+O('x^N)); Vec(sum(k=0, N, (k*x/(1-x))^k))
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PARI
a(n) = if(n==0, 1, sum(k=1, n, k^k*binomial(n-1, k-1)));
Formula
a(n) = Sum_{k=1..n} k^k * binomial(n-1,k-1) for n > 0.
a(n) ~ exp(exp(-1)) * n^n. - Vaclav Kotesovec, Jul 05 2022