A023231 Primes p such that 8*p + 7 is also prime.

2, 3, 5, 23, 29, 47, 53, 59, 89, 107, 113, 137, 179, 197, 227, 233, 257, 263, 293, 317, 359, 389, 419, 509, 557, 587, 593, 599, 617, 653, 659, 683, 839, 857, 863, 887, 947, 977, 1013, 1097, 1103, 1163, 1193, 1217, 1223, 1229, 1259, 1277, 1283, 1307, 1319, 1409

Offset: 1

Author

David W. Wilson

Keywords

• nonn
• easy

Examples

			For p = 3, 8*p + 7 = 31;
for p = 179, 8*p + 7 = 1439.
		

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A139487, A007522.

Programs

Magma

[n: n in PrimesUpTo(1500) | IsPrime(8*n+7)]; // Vincenzo Librandi, Nov 20 2010

Maple

a := proc (n) if isprime(n) = true and isprime(8*n+7) = true then n else end if end proc: seq(a(n), n = 1 .. 1500); # Emeric Deutsch, Dec 30 2008

Mathematica

Select[Prime@Range@500, PrimeQ[8 # + 7] &] (* Vincenzo Librandi, May 19 2014 *)

Extensions

Edited by N. J. A. Sloane, Mar 11 2009 at the suggestion of R. J. Mathar