OFFSET
1,2
FORMULA
a(n) = [x^n] Sum_{k>0} x^k/(1 - (k*x)^k)^n.
MATHEMATICA
a[n_] := DivisorSum[n, (n/#)^(n-n/#) * Binomial[# + n - 2, n - 1] &]; Array[a, 25] (* Amiram Eldar, Jul 12 2023 *)
PROG
(PARI) a(n) = sumdiv(n, d, (n/d)^(n-n/d)*binomial(d+n-2, n-1));
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Jun 14 2023
STATUS
approved