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

2,3

Links

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

Formula

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

Example

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

Mathematica

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

Crossrefs

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

Sequence in context: A300862 A151863 A365407 * A134142 A353390 A298310

Adjacent sequences: A366779 A366780 A366781 * A366783 A366784 A366785

Keyword

nonn

Author

Sean A. Irvine, Oct 22 2023

Status

approved