OFFSET
1,2
LINKS
Seiichi Manyama, Table of n, a(n) for n = 1..386
FORMULA
E.g.f.: Sum_{k>0} (k * x)^k/(k! * (1 - x^k)).
If p is prime, a(p) = p^p + p! = A053042(p).
MATHEMATICA
a[n_] := n! * DivisorSum[n, #^#/#! &]; Array[a, 18] (* Amiram Eldar, Jun 10 2022 *)
PROG
(PARI) a(n) = n!*sumdiv(n, d, d^d/d!);
(PARI) my(N=20, x='x+O('x^N)); Vec(serlaplace(sum(k=1, N, (k*x)^k/(k!*(1-x^k)))))
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Jun 10 2022
STATUS
approved