A366757 a(n) is the sum of the divisors of n!-1.
1, 6, 24, 144, 720, 5040, 42096, 399000, 3753960, 47500992, 479001600, 6230615736, 87178291200, 1457696910960, 20929670124480, 379536693283440, 6510917252872320, 121831439598033840, 2432921507427445440, 53921727651043042560, 1134312679767378217920
Offset: 2
Keywords
Examples
a(5) = 144 because the divisors of 5!-1 are {1, 7, 17, 119}.
Programs
-
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 *)
-
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