A063910 Primes p such that 2*p - 7 is also prime.

5, 7, 13, 19, 37, 43, 67, 73, 79, 103, 109, 139, 157, 193, 223, 277, 307, 313, 349, 367, 373, 379, 397, 409, 433, 457, 463, 487, 499, 523, 547, 619, 643, 727, 733, 739, 769, 787, 853, 877, 883, 919, 937, 997, 1009, 1069, 1093, 1123, 1129, 1237

Offset: 1

Author

N. J. A. Sloane, Aug 31 2001

Keywords

• easy
• nonn

Comments

All terms > 5 are == 1 (mod 6). - Zak Seidov, Jan 07 2014

Links

• Harry J. Smith, Table of n, a(n) for n = 1..1000

Programs

Magma

[n: n in [3..2000] | IsPrime(n) and IsPrime(2*n-7)]; // Vincenzo Librandi, Feb 02 2014

Mathematica

Select[Prime[Range[2, 2000]], PrimeQ[2 # - 7]&] (* Vincenzo Librandi, Feb 02 2014 *)

PARI

isok(p) = { isprime(p) && isprime(2*p - 7) } \\ Harry J. Smith, Sep 02 2009

Formula

A089192 INTERSECT A000040. - R. J. Mathar, Mar 23 2017