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A120481
Number of distinct 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
OFFSET
1,3
COMMENTS
Prime divisors counted without multiplicity. - Harvey P. Dale, May 25 2020
LINKS
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}]
Table[PrimeNu[Fibonacci[n]+LucasL[n]], {n, 100}] (* Harvey P. Dale, May 25 2020 *)
CROSSREFS
Sequence in context: A365836 A331244 A316845 * A369067 A356647 A219644
KEYWORD
nonn
AUTHOR
Ryan Propper, Jul 21 2006
EXTENSIONS
Definition clarified by Harvey P. Dale, May 25 2020
STATUS
approved