OFFSET
1,2
LINKS
Seiichi Manyama, Table of n, a(n) for n = 1..386
FORMULA
a(n) = Sum_{d|n} d^(d+n/d-1) * binomial(d,n/d-1).
If p is an odd prime, a(p) = p^p.
MATHEMATICA
a[n_] := DivisorSum[n, #^(#+n/#-1) * Binomial[#, n/# - 1] &]; Array[a, 20] (* Amiram Eldar, Aug 09 2023 *)
PROG
(PARI) my(N=20, x='x+O('x^N)); Vec(sum(k=1, N, (k*x*(1+k*x^k))^k))
(PARI) a(n) = sumdiv(n, d, d^(d+n/d-1)*binomial(d, n/d-1));
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Feb 17 2023
STATUS
approved