A193291 - OEIS

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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

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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