OFFSET
0,5
LINKS
Winston de Greef, Table of n, a(n) for n = 0..630
FORMULA
a(n) = Sum_{k=1..floor(n/2)} k^(n-2*k) * binomial(n-k-1,k-1) for n > 0.
MATHEMATICA
Join[{1}, Table[Sum[Binomial[n-k-1, k-1] * k^(n-2*k), {k, 0, n/2}], {n, 1, 40}]] (* Vaclav Kotesovec, Feb 20 2023 *)
PROG
(PARI) my(N=30, x='x+O('x^N)); Vec(sum(k=0, N, (x^2/(1-k*x))^k))
(PARI) a(n) = if(n==0, 1, sum(k=1, n\2, k^(n-2*k)*binomial(n-k-1, k-1)));
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Feb 17 2023
STATUS
approved