

A134787


Numbers n such that Fibonacci(prime(n)) is not prime.


20



1, 8, 11, 12, 13, 16, 17, 18, 19, 20, 21, 22, 24, 25, 26, 27, 28, 29, 30, 31, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 85, 86
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OFFSET

1,2


LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..1000


MATHEMATICA

k = {}; Do[If[ ! PrimeQ[Fibonacci[Prime[n]]], AppendTo[k, n]], {n, 1, 100}]; k
Select[Range[90], !PrimeQ[Fibonacci[Prime[#]]]&] (* Harvey P. Dale, Oct 16 2016 *)


PROG

(MAGMA) [n: n in [1..100] not IsPrime(Fibonacci(NthPrime(n)))]; // Vincenzo Librandi, Jan 18 2013
(PARI) is(n)=!isprime(fibonacci(prime(n))) \\ Charles R Greathouse IV, Feb 03 2014


CROSSREFS

Cf. A050937, A090819.
Sequence in context: A156925 A077060 A123939 * A249104 A191887 A122195
Adjacent sequences: A134784 A134785 A134786 * A134788 A134789 A134790


KEYWORD

nonn,easy


AUTHOR

Artur Jasinski, Nov 12 2007


EXTENSIONS

Definition corrected by N. J. A. Sloane, Nov 12 2007


STATUS

approved



