A134787 Numbers n such that Fibonacci(prime(n)) is not prime.

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

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: A347313 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