OFFSET
1,2
FORMULA
E.g.f.: Sum_{k>=1} (k * x)^k/(k - x^k).
MATHEMATICA
a[n_] := n! * DivisorSum[n, #^(# - n/#) &]; Array[a, 16] (* Amiram Eldar, Aug 21 2022 *)
PROG
(PARI) a(n) = n!*sumdiv(n, d, d^(d-n/d));
(PARI) my(N=20, x='x+O('x^N)); Vec(serlaplace(sum(k=1, N, (k*x)^k/(k-x^k))))
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Aug 21 2022
STATUS
approved