A144487 Primes of the form 2^k + 15.

17, 19, 23, 31, 47, 79, 271, 1039, 2063, 4111, 32783, 65551, 4194319, 8388623, 67108879, 1073741839, 4294967311, 1099511627791, 4398046511119, 70368744177679, 2305843009213693967, 4722366482869645213711, 75557863725914323419151

Offset: 1

Author

Vincenzo Librandi, Dec 09 2008

Keywords

• nonn
• easy

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..37

Crossrefs

Cf. A000040, A057197 (numbers k such that 2^k + 15 is prime). [From Klaus Brockhaus, Dec 11 2008]

Programs

Magma

[a: n in [1..100] | IsPrime(a) where a is 2^n+15]; // Vincenzo Librandi, Feb 23 2014

Mathematica

Select[2^Range[0,200]+15,PrimeQ] (* Vladimir Joseph Stephan Orlovsky, Feb 03 2012 *)
Select[Table[2^n + 15, {n, 1, 300}], PrimeQ] (* Vincenzo Librandi, Feb 23 2014 *)

PARI

{for(n=0, 72, if(isprime(k=2^n+15), print1(k, ",")))}

Formula

a(n) = 2^A057197(n) + 15. - Elmo R. Oliveira, Nov 08 2023

Extensions

Edited by Klaus Brockhaus and R. J. Mathar, Dec 10 2008

Definition simplified by Jon E. Schoenfield, Jun 17 2010