A051507 Primes p such that p*q+2 is prime, where q is next prime after p.

3, 5, 7, 13, 19, 67, 149, 179, 229, 239, 241, 269, 277, 307, 313, 397, 401, 419, 439, 487, 569, 613, 643, 701, 823, 863, 887, 1051, 1289, 1319, 1489, 1609, 1693, 1783, 1873, 1999, 2143, 2239, 2309, 2423, 2539, 2549, 2593, 2617, 2729, 2753, 2819

Offset: 1

Author

N. J. A. Sloane

Keywords

• nonn
• easy

Links

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

Crossrefs

Cf. A048880.

Programs

Mathematica

Prime[Select[Range[1000], PrimeQ[Prime[#]*Prime[# + 1] + 2] &]]
Reap[Do[If[PrimeQ[(p=Prime[k])*Prime[k+1]+2],Sow[p]],{k,1,430}]][[2,1]] (* Zak Seidov, Dec 05 2010 *)

PARI

p=2;forprime(q=3,1e4,if(isprime(p*q+2),print1(p", ")); p=q) \\ Charles R Greathouse IV, May 01 2011

Sage

A051507 = list(p for p in primes(10**4) if is_prime(p*next_prime(p)+2)) # D. S. McNeil, Dec 04 2010