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A090206 Nonprime Fibonacci numbers. 9
0, 1, 1, 8, 21, 34, 55, 144, 377, 610, 987, 2584, 4181, 6765, 10946, 17711, 46368, 75025, 121393, 196418, 317811, 832040, 1346269, 2178309, 3524578, 5702887, 9227465, 14930352, 24157817, 39088169 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

COMMENTS

It is possible to find a run of at least length n (not necessarily exactly n) such that n consecutive terms in this sequence are also consecutive in the sequence of Fibonacci numbers. However, it is not possible for such a run to be of exactly length n if n is even. - Alonso del Arte, Nov 23 2010

Some terms of this sequence have prime indices in the sequence of Fibonacci numbers (A000045), see A050937. - Alonso del Arte, Aug 16 2013

LINKS

Table of n, a(n) for n=1..30.

EXAMPLE

34 is in the sequence as it is a Fibonacci number and it is composite, the product of 2 and 17.

55 is in the sequence as it is a Fibonacci number and it is composite, the product of 5 and 11.

89 is not in the sequence because, although it is a Fibonacci number, it is prime.

MATHEMATICA

Select[Fibonacci[Range[0, 50]], !PrimeQ[#] &] (* Vladimir Joseph Stephan Orlovsky, Jul 22 2008 *)

CROSSREFS

Cf. A000045, A005478, A050937, A182602.

Sequence in context: A271921 A003249 A134862 * A139590 A154894 A241986

Adjacent sequences:  A090203 A090204 A090205 * A090207 A090208 A090209

KEYWORD

easy,nonn

AUTHOR

Felix Tubiana (fat2(AT)columbia.edu), Jan 22 2004

STATUS

approved

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Last modified November 18 09:17 EST 2017. Contains 294879 sequences.