OFFSET
1,1
COMMENTS
If m == 1, 2 or 3 (mod 4) then F(m) is not divisible by 3.
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
FORMULA
If k == 1 or 2 (mod 3) then a(3^m*k) = 3^(m+1) for m>=0.
a(n) = 3^A051064(n) (conjectured). - Michel Marcus, May 17 2022
Conjecture: a(n) = (sigma(3*n) - sigma(n))/(sigma(3*n) - 3*sigma(n)), where sigma(n) = A000203(n). Equivalently, a(n) = A088838(n) - A074724(n). - Peter Bala, Jun 10 2022
MATHEMATICA
Table[3^IntegerExponent[Fibonacci[4n], 3], {n, 100}] (* Harvey P. Dale, Jun 03 2012 *)
PROG
(PARI) a(n) = 3^valuation(fibonacci(4*n), 3); \\ Michel Marcus, May 13 2022
CROSSREFS
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Sep 04 2002
STATUS
approved