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A083019
Number of common divisors of n and F(n) where F(n) denotes the n-th Fibonacci number.
1
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
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
KEYWORD
nonn,easy
AUTHOR
Benoit Cloitre, May 31 2003
STATUS
approved