A193291 Number of even divisors of Fibonacci(n).

0, 0, 1, 0, 0, 3, 0, 0, 2, 0, 0, 12, 0, 0, 4, 0, 0, 12, 0, 0, 4, 0, 0, 60, 0, 0, 8, 0, 0, 48, 0, 0, 4, 0, 0, 128, 0, 0, 4, 0, 0, 48, 0, 0, 16, 0, 0, 288, 0, 0, 4, 0, 0, 96, 0, 0, 16, 0, 0, 768, 0, 0, 16, 0, 0, 48, 0, 0, 16, 0, 0, 1280, 0, 0, 24, 0, 0, 96, 0

Offset

1,6

Links

Amiram Eldar, Table of n, a(n) for n = 1..1000

Formula

a(n) = A183063(A000045(n)). - Amiram Eldar, Sep 03 2019

Example

a(6) = 3 because Fibonacci(6) = 8 and the 3 even divisors are {2, 4, 8}.

Mathematica

a[n_] := Block[{d = Divisors[Fibonacci[n]]}, Count[EvenQ[d], True]]; Table[a[n], {n, 110}]

Prog

(PARI) a(n)=if(n%3, 0, numdiv(fibonacci(n)/2)) \\ Charles R Greathouse IV, Jul 30 2011

Crossrefs

Cf. A000045, A183063.

Sequence in context: A344118 A212221 A343088 * A096936 A115979 A067168

Adjacent sequences: A193288 A193289 A193290 * A193292 A193293 A193294

Keyword

nonn

Author

Michel Lagneau, Jul 21 2011

Status

approved