OFFSET
1,2
LINKS
Seiichi Manyama, Table of n, a(n) for n = 1..291
FORMULA
E.g.f.: Sum_{k>0} (exp((k * x)^k) - 1)/k^k.
If p is prime, a(p) = 1 + p! = A038507(p).
MATHEMATICA
a[n_] := n! * DivisorSum[n, #^(n - #)/(n/#)! &]; Array[a, 19] (* Amiram Eldar, Jun 10 2022 *)
PROG
(PARI) a(n) = n!*sumdiv(n, d, d^(n-d)/(n/d)!);
(PARI) my(N=20, x='x+O('x^N)); Vec(serlaplace(sum(k=1, N, (exp((k*x)^k)-1)/k^k)))
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Jun 10 2022
STATUS
approved