A023230 Numbers k such that k and 8*k + 5 are both prime.

3, 7, 13, 19, 43, 67, 103, 109, 127, 139, 151, 181, 193, 199, 211, 223, 241, 277, 283, 349, 379, 397, 421, 433, 439, 463, 577, 601, 607, 613, 619, 727, 733, 787, 829, 853, 883, 967, 991, 1033, 1039, 1117, 1201, 1237, 1291, 1303, 1399, 1429, 1459, 1531, 1567, 1579

Offset: 1

Author

David W. Wilson

Keywords

• nonn
• easy

Links

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

Crossrefs

Cf. A007521 (primes of form 8n+5), A105133 (numbers n such that 8n+5 is prime).

Programs

Magma

[ p: p in PrimesUpTo(1580) | IsPrime(8*p+5) ]; // Klaus Brockhaus, Dec 21 2008

Mathematica

lst={}; Do[p=Prime[n]; If[PrimeQ[8*p+5],AppendTo[lst,p]],{n,6!}]; lst (* Vladimir Joseph Stephan Orlovsky, Aug 16 2009 *)
Select[Prime [Range[0, 300]], PrimeQ[8# + 5] &] (* Vincenzo Librandi, Sep 25 2012 *)

PARI

select(p->isprime(8*p+5),primes(1000)) \\ Charles R Greathouse IV, Sep 25 2012