OFFSET

1,2

COMMENTS

All prime Lucas numbers A000032[n] have indices that are prime, zero or a power of 2. It is a conjecture that all indices of prime Lucas numbers are prime, except n = 0, 4, 8, 16.

Indices of prime Lucas numbers are listed in A001606[n] = {0,2,4,5,7,8,11,13,16,17,19,31,37,41,47,53,61,...}.

Primes in a(n) are listed in A123677[n] = {3,5,7,11,13,71,113,643,769,13681,...} Primes p such that Lucas[Prime[p]] is prime.

FORMULA

a(n) = PrimePi(A001606(n+4)) for n>5.

MATHEMATICA

Select[ Range[300], PrimeQ[ Fibonacci[ Prime[ # ] - 1 ] + Fibonacci[ Prime[ # ] + 1 ]] & ]

CROSSREFS

KEYWORD

nonn

AUTHOR

Alexander Adamchuk, Aug 07 2006, Oct 05 2006

EXTENSIONS

a(52)-a(60) (from A001606) from Jens Kruse Andersen, Jul 24 2014

STATUS

approved