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A367493
a(n) = Sum_{d|n} (n-d)^n.
2
0, 1, 8, 97, 1024, 20450, 279936, 7509953, 144295424, 4570291850, 100000000000, 4491754172274, 106993205379072, 5221973073321002, 171975117132398592, 8931527427394008833, 295147905179352825856, 20290116242888952838355, 708235345355337676357632, 51879761166564630630389778
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