A363831 Number of divisors of A000129(n) (Pell numbers).

1, 2, 2, 6, 2, 8, 3, 16, 4, 8, 2, 72, 2, 12, 12, 40, 4, 32, 4, 96, 12, 16, 4, 384, 8, 16, 16, 144, 2, 288, 8, 96, 8, 32, 12, 1536, 8, 16, 16, 1024, 2, 288, 4, 384, 96, 32, 4, 3840, 12, 64, 32, 192, 2, 256, 32, 768, 32, 8, 2, 41472, 8, 64, 96, 896, 64, 256, 4

Offset

1,2

Links

Amiram Eldar, Table of n, a(n) for n = 1..630 (calculated using Jon E. Schoenfield's a-file at A000129)

Formula

a(n) = sigma0(Pell(n)) = A000005(A000129(n)).

Example

a(9)=4 because Pell(9)=985 has divisors {1, 5, 197, 985}.

Mathematica

DivisorSigma[0, LinearRecurrence[{2, 1}, {1, 2}, 67]] (* Stefano Spezia, Oct 19 2023 *)

Crossrefs

Cf. A000005, A000129, A272040, A363829.

Sequence in context: A293514 A028330 A293524 * A233591 A071052 A305984

Adjacent sequences: A363828 A363829 A363830 * A363832 A363833 A363834

Keyword

nonn

Author

Tyler Busby, Oct 19 2023

Status

approved