A083019 Number of common divisors of n and F(n) where F(n) denotes the n-th Fibonacci number.

1, 1, 1, 1, 2, 2, 1, 1, 1, 2, 1, 6, 1, 1, 2, 1, 1, 2, 1, 2, 1, 1, 1, 8, 3, 1, 1, 1, 1, 4, 1, 1, 1, 1, 2, 9, 1, 1, 1, 2, 1, 2, 1, 1, 2, 1, 1, 10, 1, 3, 1, 1, 1, 2, 2, 2, 1, 1, 1, 12, 1, 1, 1, 1, 2, 2, 1, 1, 1, 2, 1, 12, 1, 1, 3, 1, 1, 2, 1, 2, 1, 1, 1, 6, 2, 1, 1, 1, 1, 4, 2, 1, 1, 1, 2, 12, 1, 1, 1, 3, 1, 2, 1

Offset

1,5

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Formula

a(n) = A000005(A104714(n)). - Amiram Eldar, Jun 09 2022

Mathematica

Table[Length[Intersection[Divisors[n], Divisors[Fibonacci[n]]]], {n, 120}] (* Harvey P. Dale, Aug 24 2014 *)
a[n_] := DivisorSigma[0, GCD[n, Fibonacci[n]]]; Array[a, 100] (* Amiram Eldar, Oct 18 2019 *)

Prog

(PARI) a(n) = length(setintersect(divisors(n), divisors(fibonacci(n)))); \\ Michel Marcus, Dec 04 2013

Crossrefs

Cf. A000005, A000045, A104714.

Sequence in context: A236344 A333124 A274109 * A137865 A052494 A317756

Adjacent sequences: A083016 A083017 A083018 * A083020 A083021 A083022

Keyword

nonn,easy

Author

Benoit Cloitre, May 31 2003

Status

approved