A366668 Sum of the divisors of 10^n+1.

3, 12, 102, 1344, 10212, 109104, 1010004, 10909104, 105882372, 1413350400, 10102223208, 114737461440, 1021097900424, 10921790676000, 104844305394000, 1355394166984704, 10073631600468000, 110177492439680640, 1010002989998020008, 10909090909090909104

Offset: 0

Author

Sean A. Irvine, Oct 15 2023

Keywords

• nonn

Examples

			a(3)=1344 because 10^3+1 has divisors {1, 7, 11, 13, 77, 91, 143, 1001}.
		

Links

• Max Alekseyev, Table of n, a(n) for n = 0..331

Crossrefs

Cf. A000203, A003021, A057934, A062397, A102146, A119704, A344897, A366666.

Programs

Maple

a:=n->numtheory[sigma](10^n+1):
seq(a(n), n=0..100);

Mathematica

DivisorSigma[1, 10^Range[0,19] + 1] (* Paul F. Marrero Romero, Nov 12 2023 *)

Formula

a(n) = sigma(10^n+1) = A000203(A062397(n)).