OFFSET
1,3
FORMULA
a(n) = Sum_{k=0..n} (-1)^k*binomial(n,k)*n^(n-k)*sigma_k(n).
MATHEMATICA
a[n_]:=Sum[(n-d)^n, {d, Divisors[n]}]; Array[a, 20] (* Stefano Spezia, Nov 20 2023 *)
PROG
(Python)
from sympy import divisors
def A367493(n): return sum((n-d)**n for d in divisors(n, generator=True))
CROSSREFS
KEYWORD
nonn
AUTHOR
Chai Wah Wu, Nov 20 2023
STATUS
approved