

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
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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

Cf. A000045, A193291.
Sequence in context: A295878 A294931 A336856 * A275297 A300667 A129687
Adjacent sequences: A193289 A193290 A193291 * A193293 A193294 A193295


KEYWORD

nonn


AUTHOR

Michel Lagneau, Jul 21 2011


STATUS

approved



