A121606 Indices n such that A018910[n] = (Fibonacci[n+3] + 2) are primes.

1, 2, 5, 11, 19, 37, 73, 85, 155, 193, 227, 233, 257, 785, 797, 1277, 2371, 2771, 4213, 9107

Offset: 1

Author

Alexander Adamchuk, Aug 09 2006

Keywords

• nonn

Comments

A018910[n] is Pisot sequence L(4,5). Prime Pisot L(4,5) numbers are A018910[a(n)] = Fibonacci[a(n) + 3 ] + 2 = {5,7,23,379,17713,102334157,...} = A121605[n]. Most listed a(n) are prime except a(8),a(9),a(14),a(18).

Crossrefs

Cf. A121605, A018910, A048584.

Programs

Mathematica

Do[f=Fibonacci[n+3]+2;If[PrimeQ[f],Print[n]],{n,1,3000}]
Select[Range[10000],PrimeQ[Fibonacci[#+3]+2]&] (* Harvey P. Dale, Jul 01 2019 *)

Extensions

More terms from Harvey P. Dale, Jul 01 2019