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

2,2

Links

Table of n, a(n) for n=2..22.

Formula

a(n) = sigma(n!-1) = A000203(A033312(n)).

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

Cf. A033312, A000203, A064145, A062569, A366758.

Sequence in context: A188330 A126267 A026947 * A250743 A265883 A330498

Adjacent sequences: A366754 A366755 A366756 * A366758 A366759 A366760

Keyword

nonn

Author

Sean A. Irvine, Oct 20 2023

Status

approved