A366617 Sum of the divisors of 5^n+1.

3, 12, 42, 312, 942, 6264, 25284, 162000, 620460, 4961280, 16161768, 103442688, 367381884, 2441936064, 9859525284, 76963663296, 228970112844, 1526377433328, 6339280635408, 38199227335200, 144103649734968, 1285221510144000, 3894650946433800, 24349131482713344

Offset: 0

Author

Sean A. Irvine, Oct 14 2023

Keywords

• nonn

Examples

			a(3)=312 because 5^3+1 has divisors {1, 2, 3, 6, 7, 9, 14, 18, 21, 42, 63, 126}.
		

Links

• Max Alekseyev, Table of n, a(n) for n = 0..471

Crossrefs

Cf. A000203, A034474, A057939, A074478, A366613, A366615, A366616, A366618.

Cf. A069061, A366578, A366607, A366629, A366638, A366657, A366666, A366668, A366689, A366715.

Programs

Maple

a:=n->numtheory[sigma](5^n+1):
seq(a(n), n=0..100);

Mathematica

DivisorSigma[1, 5^Range[0, 30] + 1] (* Paolo Xausa, Jul 03 2024 *)

Formula

a(n) = sigma(5^n+1) = A000203(A034474(n)).