OFFSET
2,2
EXAMPLE
a(5) = 144 because the divisors of 5!-1 are {1, 7, 17, 119}.
MAPLE
a:=n->numtheory[sigma](n!-1):
seq(a(n), n=2..30);
MATHEMATICA
DivisorSigma[1, Range[2, 25]!-1] (* Paolo Xausa, Oct 21 2023 *)
PROG
(Python)
from math import factorial
from sympy import divisor_sigma
def A366757(n): return divisor_sigma(factorial(n)-1) # Chai Wah Wu, Oct 20 2023
CROSSREFS
KEYWORD
nonn
AUTHOR
Sean A. Irvine, Oct 20 2023
STATUS
approved