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A081979 Smallest Fibonacci number with 2n divisors, or 0 if no such number exists. 2
2, 8, 75025, 610 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Further known entries are a(12)=A000045(91); a(16)=A000045(44); a(24)=A000045(50); a(32)=A000045(30); a(36)=A000045(24); a(48)=A000045(56); a(64)=A000045(54); a(80)=A000045(36); a(96)=A000045(182); a(128)=A000045(128) ; a(168)=A000045(48); a(192)=A000045(110); a(256)=A000045(80),..., a(688128)=A000045(240) from the Kelly factorizations. - R. J. Mathar, Apr 05 2007

For n prime, a(n) = q*p^(n-1) or p^(2n-1) for some primes p and q since those are the only numbers with 2*n divisors. a(8) = 2584. - Chai Wah Wu, Dec 08 2014

LINKS

Table of n, a(n) for n=1..4.

Blair Kelly, Fibonacci Factorizations.

EXAMPLE

a(2)=8 because 8 is the smallest Fibonacci number with 4 divisors (1,2,4,8).

CROSSREFS

Cf. A081978.

Sequence in context: A007753 A272331 A256065 * A012672 A024340 A012667

Adjacent sequences:  A081976 A081977 A081978 * A081980 A081981 A081982

KEYWORD

more,nonn

AUTHOR

Amarnath Murthy, Apr 03 2003

EXTENSIONS

Corrected by Emeric Deutsch, Apr 19 2005

STATUS

approved

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Last modified July 4 16:24 EDT 2020. Contains 335448 sequences. (Running on oeis4.)