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A111079 a(n) = gcd(F(n), product{k|n,k<n} F(k)), where F(k) is k-th Fibonacci number. 0
1, 1, 1, 1, 1, 2, 1, 3, 2, 5, 1, 48, 1, 13, 10, 21, 1, 136, 1, 165, 26, 89, 1, 2016, 5, 233, 34, 1131, 1, 26840, 1, 987, 178, 1597, 65, 139536, 1, 4181, 466, 47355, 1, 1269736, 1, 53133, 10370, 28657, 1, 4358592, 13, 825275, 3194, 364179, 1, 14927768, 445 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,6

LINKS

Table of n, a(n) for n=1..55.

EXAMPLE

The proper divisors of 16 are 1, 2, 4, 8. So a(16) = gcd(F(16), F(1)*F(2)*F(4)*F(8)) = gcd(987, 1*1*3*21) = 21.

MAPLE

with(combinat): with(numtheory): a:=proc(n) local div: div:=divisors(n): gcd(fibonacci(n), product(fibonacci(div[j]), j=1..tau(n)-1)): end: seq(a(n), n=1..65); # Emeric Deutsch, Oct 12 2005

MATHEMATICA

f[n_] := GCD[Fibonacci[n], Times @@ Fibonacci /@ Most[Divisors[n]]]; Table[ f[n], {n, 55}] (* Robert G. Wilson v, Oct 12 2005 *)

CROSSREFS

Cf. A000045.

Sequence in context: A181363 A105800 A105602 * A165006 A134735 A240867

Adjacent sequences:  A111076 A111077 A111078 * A111080 A111081 A111082

KEYWORD

nonn

AUTHOR

Leroy Quet, Oct 11 2005

EXTENSIONS

More terms from Robert G. Wilson v and Emeric Deutsch, Oct 12 2005

STATUS

approved

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Last modified May 18 03:30 EDT 2022. Contains 353783 sequences. (Running on oeis4.)