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A090819 Primes p such that the p-th Fibonacci number is nonprime. 21
2, 19, 31, 37, 41, 53, 59, 61, 67, 71, 73, 79, 89, 97, 101, 103, 107, 109, 113, 127, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251, 257, 263, 269, 271, 277, 281, 283, 293 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Is it true that a(n) ~ n log n? - Charles R Greathouse IV, Aug 15 2015

LINKS

Table of n, a(n) for n=1..49.

EXAMPLE

Fibonacci(37) = 24157817 = 73*149*2221. [corrected by Bobby Jacobs, Sep 25 2017]

MATHEMATICA

Select[Prime[Range[62]], ! PrimeQ[Fibonacci[#]] &] (* Jayanta Basu, Jul 10 2013 *)

PROG

(PARI) f(n) = forprime(x=2, n, p=fibonacci(x); if(!isprime(p), print1(x", ")))

CROSSREFS

Cf. A000045, A001605.

Essentially the same as A038672.

Sequence in context: A120276 A006962 A261312 * A254897 A059697 A103058

Adjacent sequences:  A090816 A090817 A090818 * A090820 A090821 A090822

KEYWORD

easy,nonn

AUTHOR

Cino Hilliard, Feb 11 2004

EXTENSIONS

Definition corrected by Don Reble, Sep 04 2008

STATUS

approved

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Last modified June 18 20:45 EDT 2021. Contains 345121 sequences. (Running on oeis4.)