A166009 Primes of the form 7 + 2*p, where p is a prime.

11, 13, 17, 29, 41, 53, 89, 101, 113, 149, 173, 233, 269, 281, 353, 389, 401, 461, 509, 521, 569, 593, 641, 701, 773, 809, 929, 941, 1013, 1049, 1181, 1193, 1289, 1301, 1361, 1373, 1409, 1493, 1553, 1601, 1721, 1733, 1889, 1901, 1913, 1949, 1973, 2069, 2129

Offset: 1

Author

Vincenzo Librandi, Oct 04 2009

Keywords

• nonn

Comments

Starting with n=3 both a(n) and A023206(n) == 5 mod 6. - Zak Seidov, Oct 23 2009

Examples

			13 is in the sequence because 13 = 7 + 2*3 and 3 are both primes.
		

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A023206. - Zak Seidov, Oct 23 2009

Programs

Mathematica

Clear[lst,n,f] f[n_]:=PrimeQ[(n-1)/2-3]; lst={};Do[p=Prime[n];If[f[p],AppendTo[lst,p]],{n,7!}];lst (* Vladimir Joseph Stephan Orlovsky, Oct 13 2009 *)
s={11,13};Do[If[PrimeQ[n]&&PrimeQ[(n-7)/2],AppendTo[s,n]],{n,17,10^3,6}];s (* Zak Seidov, Oct 23 2009 *)
Select[2#+7&/@Prime[Range[200]],PrimeQ] (* Harvey P. Dale, Dec 15 2010 *)

PARI

lista(nn) = {forprime(p=2, nn, if (isprime(q=2*p+7), print1(q, ", ")););} \\ Michel Marcus, Nov 08 2014

Formula

a(n) = 7 + 2*A023206(n). - R. J. Mathar, Oct 05 2009

Extensions

1089 replaced with 1049 by R. J. Mathar, Oct 05 2009