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A193292 Number of odd divisors of Fibonacci(n). 3
1, 1, 1, 2, 2, 1, 2, 4, 2, 4, 2, 3, 2, 4, 4, 8, 2, 4, 4, 16, 4, 4, 2, 12, 6, 4, 8, 16, 2, 16, 4, 16, 4, 4, 8, 32, 8, 8, 4, 64, 4, 16, 2, 32, 16, 8, 2, 48, 8, 48, 4, 16, 4, 32, 16, 96, 16, 8, 4, 192, 4, 8, 16, 64, 8, 16, 8, 32, 16, 128, 4, 256, 4, 16, 24, 32 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,4
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 1..1000
FORMULA
a(n) = A001227(A000045(n)). - Michel Marcus, Jan 14 2014
EXAMPLE
a(16) = 8 because Fibonacci(16) = 987 = 3 * 7 * 47 and the 8 odd divisors are {1, 3, 7, 21, 47, 141, 329, 987}.
MATHEMATICA
f[n_] := Block[{d = Divisors[Fibonacci[n]]}, Count[OddQ[d], True]]; Table[
f[n], {n, 110}]
PROG
(PARI) a(n)=n=fibonacci(n); numdiv(n>>valuation(n, 2)) \\ Charles R Greathouse IV, Jul 30 2011
CROSSREFS
Sequence in context: A294931 A365402 A336856 * A275297 A353368 A300667
KEYWORD
nonn
AUTHOR
Michel Lagneau, Jul 21 2011
STATUS
approved

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Last modified March 29 02:23 EDT 2024. Contains 371264 sequences. (Running on oeis4.)