A366688 Number of divisors of 11^n+1.

2, 6, 4, 18, 4, 12, 16, 12, 8, 48, 8, 96, 16, 48, 32, 144, 8, 48, 32, 96, 16, 72, 16, 96, 128, 48, 8, 240, 64, 48, 64, 96, 16, 4608, 64, 1152, 128, 24, 16, 1152, 32, 48, 512, 24, 64, 3072, 64, 96, 32, 192, 64, 1152, 8, 96, 512, 6144, 128, 2304, 64, 96, 256, 48

Offset: 0

Author

Sean A. Irvine, Oct 16 2023

Keywords

• nonn

Examples

			a(4)=4 because 11^4+1 has divisors {1, 2, 7321, 14642}.
		

Links

• Max Alekseyev, Table of n, a(n) for n = 0..325

Crossrefs

Cf. A034524, A000005, A062308, A366683, A366686, A366687, A366689, A366690.

Cf. A046798, A344897, A366714.

Programs

Maple

a:=n->numtheory[tau](11^n+1):
seq(a(n), n=0..100);

Mathematica

DivisorSigma[0,11^Range[0,70]+1] (* Harvey P. Dale, Mar 17 2025 *)

PARI

a(n) = numdiv(11^n+1);

Formula

a(n) = sigma0(11^n+1) = A000005(A034524(n)).