A228145 Numbers k such that 2*Fibonacci(k) - 1 is prime.

3, 4, 8, 9, 10, 16, 18, 31, 34, 39, 41, 42, 55, 68, 79, 90, 95, 97, 114, 122, 148, 151, 160, 209, 265, 320, 329, 441, 457, 516, 529, 632, 640, 682, 712, 791, 1056, 1169, 1632, 1943, 2200, 2279, 2468, 2698, 2921, 2996, 3129, 3140, 3656, 3960, 4889, 5560, 5895

Offset: 1

Author

Vincenzo Librandi, Aug 13 2013

Keywords

• nonn

Links

• Jorge Coveiro, Table of n, a(n) for n = 1..62 (first 55 terms from Vincenzo Librandi)

Crossrefs

Cf. A000045, A124067.

Programs

Magma

[n: n in [1..1700] | IsPrime(2*Fibonacci(n)-1)];

Mathematica

Select[Range[2000], PrimeQ[2 Fibonacci[#] - 1]&]

PARI

is(n)=ispseudoprime(2*fibonacci(n)-1) \\ Charles R Greathouse IV, Jun 13 2017