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A227627
Numbers n such that F(5*n)/(5*F(n)) is prime, where F(k) is the k-th Fibonacci number.
1
2, 3, 5, 7, 13, 25, 29, 37, 47, 67, 457, 2309, 2383, 4133, 5023, 8059
OFFSET
1,1
COMMENTS
Except for n = 25, all other terms n are primes. Conjecture: this sequence is infinite. - Thomas Ordowski, Jul 18 2013
MATHEMATICA
Select[Range[1000], PrimeQ[Fibonacci[5*#]/Fibonacci[#]/5]&]
PROG
(PARI) is(n)=ispseudoprime(fibonacci(5*n)/fibonacci(n)/5) \\ Charles R Greathouse IV, Nov 25 2014
CROSSREFS
KEYWORD
nonn,more,hard
AUTHOR
Vaclav Kotesovec, Jul 18 2013
STATUS
approved