A105307 Base-2 logarithm of the number of divisors of Fibonacci(n) if that number is a power of 2, otherwise -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

Offset: 1

Author

John W. Layman, May 03 2005

Keywords

• sign

Comments

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

Examples

			F(6)=8 has 4 divisors {1,2,4,8}, so a(6) = log_2(4) = 2.
		

Crossrefs

Cf. A081979.