A175236 Primes p such that 2^p+23 is also prime.

3, 7, 79, 359, 1031, 1039, 11311, 47599

Offset: 1

Author

Vincenzo Librandi, Mar 09 2010

Keywords

• nonn
• more

Comments

a(9) > 5*10^5. - Robert Price, Sep 18 2015

Examples

			For p=3, 2^3+23=31; p=7, 2^7+23=131; p=79, 2^79+23=604462909807314587353111
		

Programs

Magma

[p: p in PrimesUpTo(1000) | IsPrime(2^p+23) ];

Mathematica

Select[Prime[Range[1000]], PrimeQ[2^#+23]&] (*Robert Price, Sep 18 2015 *)

Formula

A057203 INTERSECT A000040. [R. J. Mathar, Jul 06 2010]

Extensions

a(5)-a(6) from R. J. Mathar, Jul 06 2010

a(7)-a(8) from Robert Price, Sep 18 2015