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A120481 Number of prime divisors of F(n) + L(n), where F(n) is the n-th Fibonacci number and L(n) is the n-th Lucas number. 0
1, 1, 2, 2, 1, 2, 3, 2, 3, 2, 2, 2, 3, 3, 4, 2, 3, 3, 5, 3, 3, 2, 4, 3, 3, 4, 5, 2, 5, 3, 5, 3, 3, 4, 5, 4, 4, 3, 7, 3, 5, 2, 6, 5, 4, 2, 6, 4, 6, 3, 5, 3, 6, 5, 7, 5, 4, 3, 8, 3, 4, 5, 7, 4, 5, 4, 6, 5, 8, 3, 8, 3, 5, 5, 6, 5, 6, 3, 10, 7, 4, 2, 9, 5, 4, 4, 10, 3, 10, 5, 7, 4, 3, 7, 9, 5, 6, 6, 10, 3 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Table of n, a(n) for n=1..100.

Eric Weisstein's World of Mathematics, Fibonacci Number

Eric Weisstein's World of Mathematics, Lucas Number

EXAMPLE

F(30) + L(30) = 2692538, which has the 3 prime divisors {2, 557, 2417}, so a(30) = 3.

MATHEMATICA

Do[f = Fibonacci[n]; l = Fibonacci[n-1] + Fibonacci[n+1]; Print[Length[FactorInteger[f + l]]], {n, 100}]

CROSSREFS

Sequence in context: A227725 A331244 A316845 * A219644 A193676 A029291

Adjacent sequences:  A120478 A120479 A120480 * A120482 A120483 A120484

KEYWORD

nonn

AUTHOR

Ryan Propper, Jul 21 2006

STATUS

approved

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Last modified February 20 04:32 EST 2020. Contains 332063 sequences. (Running on oeis4.)