A090819 - OEIS

%I #29 Oct 25 2024 06:50:24

%S 2,19,31,37,41,53,59,61,67,71,73,79,89,97,101,103,107,109,113,127,139,

%T 149,151,157,163,167,173,179,181,191,193,197,199,211,223,227,229,233,

%U 239,241,251,257,263,269,271,277,281,283,293,307,311,313,317,331,337,347,349

%N Primes p such that the p-th Fibonacci number is nonprime.

%C Is it true that a(n) ~ n log n? - _Charles R Greathouse IV_, Aug 15 2015

%F a(n) = prime(A134787(n)). - _Amiram Eldar_, Oct 25 2024

%e Fibonacci(37) = 24157817 = 73*149*2221. [corrected by _Bobby Jacobs_, Sep 25 2017]

%t Select[Prime[Range[62]], ! PrimeQ[Fibonacci[#]] &] (* _Jayanta Basu_, Jul 10 2013 *)

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

%Y Cf. A000045, A001605, A134787.

%Y Essentially the same as A038672.

%K easy,nonn

%O 1,1

%A _Cino Hilliard_, Feb 11 2004

%E Definition corrected by _Don Reble_, Sep 04 2008