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A134787 Numbers n such that Fibonacci(prime(n)) is not prime. 20

%I

%S 1,8,11,12,13,16,17,18,19,20,21,22,24,25,26,27,28,29,30,31,34,35,36,

%T 37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,

%U 60,61,62,63,64,65,66,67,68,69,70,71,73,74,75,76,77,78,79,80,81,82,85,86

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

%H Vincenzo Librandi, <a href="/A134787/b134787.txt">Table of n, a(n) for n = 1..1000</a>

%t k = {}; Do[If[ ! PrimeQ[Fibonacci[Prime[n]]], AppendTo[k, n]], {n, 1, 100}]; k

%t Select[Range[90],!PrimeQ[Fibonacci[Prime[#]]]&] (* _Harvey P. Dale_, Oct 16 2016 *)

%o (MAGMA) [n: n in [1..100]| not IsPrime(Fibonacci(NthPrime(n)))]; // _Vincenzo Librandi_, Jan 18 2013

%o (PARI) is(n)=!isprime(fibonacci(prime(n))) \\ _Charles R Greathouse IV_, Feb 03 2014

%Y Cf. A050937, A090819.

%K nonn,easy

%O 1,2

%A _Artur Jasinski_, Nov 12 2007

%E Definition corrected by _N. J. A. Sloane_, Nov 12 2007

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Last modified June 20 10:03 EDT 2021. Contains 345162 sequences. (Running on oeis4.)