OFFSET
1,2
LINKS
Seiichi Manyama, Table of n, a(n) for n = 1..386
FORMULA
G.f.: Sum_{k>=1} k^k*x^k/(1 + x^k).
a(n) ~ n^n. - Vaclav Kotesovec, Nov 09 2018
MATHEMATICA
Table[Sum[(-1)^(n/d + 1) d^d, {d, Divisors[n]}], {n, 20}]
nmax = 20; Rest[CoefficientList[Series[Sum[k^k x^k/(1 + x^k), {k, 1, nmax}], {x, 0, nmax}], x]]
PROG
(PARI) a(n) = sumdiv(n, d, (-1)^(n/d+1)*d^d); \\ Michel Marcus, Nov 09 2018
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Nov 08 2018
STATUS
approved