A366782 Number of divisors of A000073(n) (tribonacci numbers).

1, 1, 2, 3, 2, 2, 8, 6, 5, 2, 4, 24, 6, 8, 21, 16, 3, 8, 16, 12, 8, 12, 8, 6, 12, 12, 8, 80, 12, 24, 168, 20, 16, 12, 144, 24, 32, 16, 128, 12, 4, 16, 4, 32, 32, 16, 96, 320, 4, 48, 72, 216, 8, 32, 256, 48, 4, 8, 32, 48, 384, 32, 96, 576, 12, 4, 16, 36, 8, 8

Offset: 2

Author

Sean A. Irvine, Oct 22 2023

Keywords

• nonn

Examples

			a(8)=8 because the 8th tribonacci number 24 has divisors {1, 2, 3, 4, 6, 8, 12, 24}.
		

Links

• Amiram Eldar, Table of n, a(n) for n = 2..365

Crossrefs

Cf. A000005, A000073, A366780, A366781, A366783, A063375.

Programs

Mathematica

DivisorSigma[0, LinearRecurrence[{1, 1, 1}, {1, 1, 2}, 70]] (* Amiram Eldar, Oct 23 2023 *)

Formula

a(n) = A000005(A000073(n)).