OFFSET
1,2
LINKS
Seiichi Manyama, Table of n, a(n) for n = 1..599
FORMULA
G.f.: Sum_{k>=1} x^k/(1 - (k * x)^k).
If p is prime, a(p) = 2.
MATHEMATICA
a[n_] := DivisorSum[n, #^(n - #) &]; Array[a, 30] (* Amiram Eldar, Mar 17 2021 *)
PROG
(PARI) a(n) = sumdiv(n, d, d^(n-d));
(PARI) my(N=40, x='x+O('x^N)); Vec(sum(k=1, N, x^k/(1-(k*x)^k)))
(Python)
from sympy import divisors
def A342628(n): return sum(d**(n-d) for d in divisors(n, generator=True)) # Chai Wah Wu, Jun 19 2022
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Mar 16 2021
STATUS
approved