A366613 Sum of the divisors of 5^n-1.

7, 60, 224, 1736, 6048, 49920, 136724, 1107792, 3718400, 27060480, 85449224, 869499904, 2136230474, 15820920000, 61359427584, 461863805760, 1338408456700, 13177159680000, 33558717136896, 301282248701952, 863701914880000, 6313641012910080, 20863951122979048

Offset: 1

Author

Sean A. Irvine, Oct 14 2023

Keywords

• nonn

Examples

			a(3)=224 because 5^3-1 has divisors {1, 2, 4, 31, 62, 124}.
		

Links

• Max Alekseyev, Table of n, a(n) for n = 1..502

Crossrefs

Cf. A024049, A000203, A057956, A059887, A074479, A143665, A218357, A295502, A366611, A366612.

Cf. A075708, A366576, A366603, A366622, A366634, A366653, A366662, A102146, A366684, A366710.

Programs

Maple

a:=n->numtheory[sigma](5^n-1):
seq(a(n), n=1..100);

Mathematica

DivisorSigma[1, 5^Range[30]-1]

Formula

a(n) = sigma(5^n-1) = A000203(A024049(n)).