

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: A003249 A134862 A302253 * 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



