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