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A060865
a(n) is the exact power of 2 that divides the n-th Fibonacci number (A000045).
4
1, 1, 2, 1, 1, 8, 1, 1, 2, 1, 1, 16, 1, 1, 2, 1, 1, 8, 1, 1, 2, 1, 1, 32, 1, 1, 2, 1, 1, 8, 1, 1, 2, 1, 1, 16, 1, 1, 2, 1, 1, 8, 1, 1, 2, 1, 1, 64, 1, 1, 2, 1, 1, 8, 1, 1, 2, 1, 1, 16, 1, 1, 2, 1, 1, 8, 1, 1, 2, 1, 1, 32, 1, 1, 2, 1, 1, 8, 1, 1, 2, 1, 1, 16, 1, 1, 2, 1, 1, 8, 1, 1, 2, 1, 1, 128, 1, 1, 2, 1
OFFSET
1,3
LINKS
FORMULA
If n is not divisible by 3 then a(n) = 1, if n = 3 * 2^k * (2m + 1) then a(n) = 2 if k=0 or 2^(k+2) if k>0.
a(n) = F(n) / A174883(n). - Franklin T. Adams-Watters, Jan 24 2012
a(n) = A006519(A000045(n)). - Michel Marcus, Jul 30 2013
a(3n) = 2^A090740(n). - Robert Israel, Dec 28 2015
EXAMPLE
a(12) = 16 because the 12th Fibonacci number is 144 and 144 = 9*16.
MAPLE
seq(2^padic:-ordp(combinat:-fibonacci(n), 2), n=1..100); # Robert Israel, Dec 28 2015
PROG
(PARI) a(n)=2^valuation(fibonacci(n), 2) \\Michel Marcus, Jul 30 2013
CROSSREFS
Cf. A000045, A060904(n) = 5^A112765(n), A090740.
Sequence in context: A007375 A294808 A294605 * A078689 A230069 A276813
KEYWORD
nonn,easy
AUTHOR
Ahmed Fares (ahmedfares(AT)my-deja.com), May 04 2001
EXTENSIONS
More terms from Larry Reeves (larryr(AT)acm.org), May 07 2001
STATUS
approved