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A105800
Greatest Fibonacci number that is a proper divisor of the n-th Fibonacci number; a(1) = a(2) = 1.
8
1, 1, 1, 1, 1, 2, 1, 3, 2, 5, 1, 8, 1, 13, 5, 21, 1, 34, 1, 55, 13, 89, 1, 144, 5, 233, 34, 377, 1, 610, 1, 987, 89, 1597, 13, 2584, 1, 4181, 233, 6765, 1, 10946, 1, 17711, 610, 28657, 1, 46368, 13, 75025, 1597, 121393, 1, 196418, 89, 317811, 4181, 514229, 1, 832040, 1
OFFSET
1,6
COMMENTS
a(A001605(n)) = 1.
LINKS
Eric Weisstein's World of Mathematics, Fibonacci Number
FORMULA
From Antti Karttunen, Jan 11 2017: (Start)
a(n) = A280686(A000045(n)).
a(n) = A000045(A032742(n)). [Because A000045 is a divisibility sequence.]
a(A032742(n)) = A280688(n).
(End)
MATHEMATICA
nn=70; Join[{1, 1}, With[{fibs=Fibonacci[Range[nn]]}, Table[ Max[ Intersection[ Most[Divisors[fibs[[n]]]], fibs]], {n, 3, nn}]]] (* Harvey P. Dale, Apr 10 2012 *)
CROSSREFS
Cf. A046022 (gives the positions of ones).
Sequence in context: A321270 A030067 A181363 * A365859 A105602 A111079
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Apr 20 2005
STATUS
approved