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

1,1

Comments

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

Links

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

Formula

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

Example

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

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 *)

Prog

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

Crossrefs

Cf. A023206. - Zak Seidov, Oct 23 2009

Sequence in context: A356383 A335976 A052031 * A240107 A105892 A111337

Adjacent sequences: A166006 A166007 A166008 * A166010 A166011 A166012

Keyword

nonn

Author

Vincenzo Librandi, Oct 04 2009

Extensions

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

Status

approved