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A105307 Log base 2 of the number of divisors of Fibonacci[n] if that number is a power of 2, else -1. 1
0, 0, 1, 1, 1, 2, 1, 2, 2, 2, 1, -1, 1, 2, 3, 3, 1, 4, 2, 4, 3, 2, 1, -1, -1, 2, 4, 4, 1, 6, 2, 4, 3, 2, 3, -1, 3, 3, 3, 6, 2, 6, 1, 5, 5, 3, 1, -1, 3, -1, 3, 4, 2, 7, 4, -1, 5, 3, 2, -1, 2, 3, 5, 6, 3, 6, 3, 5, 5, 7, 2, -1, 2, 4, -1, 5, 4, 7, 2, 9, 7, 3, 1, -1, 4, 3, 4, 9, 2, 11, -1, 6, 4, 2, 6, -1, 4, 5, 6, -1, 2, 7, 3, 7, 7, 3, 2, -1, 2, -1, 5, -1, 2, 9, 4, 6, 6, 5, 3 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,6

COMMENTS

It appears that the number of divisors of most Fibonacci numbers is a power of 2.

LINKS

Table of n, a(n) for n=1..119.

EXAMPLE

F(6)=8 has 4 divisors {1,2,4,8}, so a(6)=log base 2 of 4=2

CROSSREFS

Cf. A081979.

Sequence in context: A180580 A026513 A106028 * A281012 A304943 A248597

Adjacent sequences:  A105304 A105305 A105306 * A105308 A105309 A105310

KEYWORD

sign

AUTHOR

John W. Layman, May 03 2005

STATUS

approved

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Last modified January 19 21:47 EST 2020. Contains 331066 sequences. (Running on oeis4.)