A125272 Primes p such that 3p - 2 and 3p + 2 are also primes.

3, 5, 7, 13, 23, 37, 43, 103, 127, 163, 167, 257, 293, 313, 337, 433, 523, 757, 797, 887, 953, 1013, 1063, 1153, 1283, 1303, 1307, 1483, 1597, 1657, 1667, 1693, 1723, 1783, 1913, 2003, 2333, 2347, 2557, 2897, 2927, 3067, 3533, 3823, 3943, 4003, 4013, 4093

Offset: 1

Author

Zak Seidov, Nov 26 2006

Keywords

• nonn
• easy

Links

• Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

Crossrefs

Intersection of A023208 and A088878.

Cf. A125215.

Programs

Magma

[p: p in PrimesUpTo(70000)| IsPrime(3*p-2)and IsPrime(3*p+2)] // Vincenzo Librandi, Jan 29 2011

Mathematica

lst={}; Do[p=Prime[n]; If[PrimeQ[3*p-2]&&PrimeQ[3*p+2],AppendTo[lst,p]],{n,7!}]; lst (* Vladimir Joseph Stephan Orlovsky, Jan 18 2009 *)
Select[Prime[Range[600]],AllTrue[3#+{2,-2},PrimeQ]&] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, May 29 2021 *)

PARI

is(n)=isprime(3*n-2)&&isprime(3*n+2)&&isprime(n) \\ Charles R Greathouse IV, Jul 02 2013

Formula

a(n) = A125215(n)/3.