A366684 Sum of the divisors of 11^n-1.

18, 360, 2880, 46128, 299646, 7113600, 35893440, 686393568, 5105934720, 80436972240, 513593801496, 14266630210560, 62197735384584, 1165770116121600, 9349887314805120, 157025981601707904, 909804651298728804, 22898038082582016000, 110086362807146183340

Offset: 1

Author

Sean A. Irvine, Oct 16 2023

Keywords

• nonn

Examples

			a(3)=2880 because 11^3-1 has divisors {1, 2, 5, 7, 10, 14, 19, 35, 38, 70, 95, 133, 190, 266, 665, 1330}.
		

Links

• Max Alekseyev, Table of n, a(n) for n = 1..316

Crossrefs

Cf. A024127, A000203, A366710, A366666, A366681, A366682, A366683, A366685.

Programs

Maple

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

Mathematica

DivisorSigma[1, 11^Range[30]-1]

Formula

a(n) = sigma(11^n-1) = A000203(A024127(n)).