A023205 Numbers m such that m and 2*m + 5 are both prime.

3, 7, 13, 19, 31, 37, 61, 67, 73, 79, 97, 103, 109, 139, 151, 163, 181, 229, 241, 271, 283, 307, 313, 367, 373, 409, 439, 457, 523, 541, 613, 643, 661, 709, 727, 733, 739, 769, 787, 811, 829, 859, 877, 937, 991, 997, 1039, 1063, 1069, 1087, 1117, 1123, 1153, 1171

Offset

1,1

Links

John Cerkan, Table of n, a(n) for n = 1..10000

Formula

a(n) == 1 (mod 6) for n>=2. - John Cerkan, Sep 07 2016

Maple

A023205:=n->`if`(isprime(n) and isprime(2*n+5), n, NULL): seq(A023205(n), n=1..3*10^3); # Wesley Ivan Hurt, Sep 08 2016

Mathematica

Select[Prime@Range@250, PrimeQ[2#+5]&] (* Vladimir Joseph Stephan Orlovsky, Apr 25 2011 *)

Prog

(Magma) [n: n in [0..100000] | IsPrime(n) and IsPrime(2*n+5)] // Vincenzo Librandi, Aug 04 2010

Crossrefs

Subsequence of primes of A089038.

Cf. A005384, A023204.

Sequence in context: A086135 A023220 A207990 * A304874 A167473 A256864

Adjacent sequences: A023202 A023203 A023204 * A023206 A023207 A023208

Keyword

nonn

Author

David W. Wilson, Jun 14 1998

Status

approved