A245801 Positive n such that Lucas(3*n) - Fibonacci(n) is a prime.

1, 2, 28, 58, 98, 118, 212, 238, 350, 478, 883, 2660, 3971, 21491

Offset

1,2

Comments

n=0 would give the prime 2 but positive n is required. Some terms correspond to probable primes. a(15) > 40000. - Jens Kruse Andersen, Aug 04 2014

Links

Table of n, a(n) for n=1..14.

Maple

with(combinat): A245801:=n->`if`(isprime(fibonacci(3*n+1)+fibonacci(3*n-1)-fibonacci(n)), n, NULL): seq(A245801(n), n=1..1000); # Wesley Ivan Hurt, Aug 04 2014

Mathematica

Select[Range[3000], PrimeQ[LucasL[3 #] - Fibonacci[#]] &]

Prog

(Magma) [n: n in [1..800] | IsPrime(Lucas(3*n) - Fibonacci(n))];
(Python)
import sympy
{print(n, end=', ') for n in range(10**3) if sympy.isprime(sympy.lucas(3*n)-sympy.fibonacci(n))} # Derek Orr, Aug 03 2014

Crossrefs

Cf. A000032, A000045, A014448.

Sequence in context: A363875 A339990 A336464 * A296245 A156471 A329595

Adjacent sequences: A245798 A245799 A245800 * A245802 A245803 A245804

Keyword

nonn,more,hard

Author

Vincenzo Librandi, Aug 02 2014

Extensions

21491 from Jens Kruse Andersen, Aug 04 2014

Status

approved