A023206 Numbers m such that m and 2*m + 7 both prime.

2, 3, 5, 11, 17, 23, 41, 47, 53, 71, 83, 113, 131, 137, 173, 191, 197, 227, 251, 257, 281, 293, 317, 347, 383, 401, 461, 467, 503, 521, 587, 593, 641, 647, 677, 683, 701, 743, 773, 797, 857, 863, 941, 947, 953, 971, 983, 1031, 1061, 1103, 1151, 1163, 1187, 1193, 1217

Offset

1,1

Comments

Subsequence of A105760. Except for the first two terms, all terms are congruent to 5 mod 6. - John Cerkan, Sep 07 2016

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Maple

A023206:=n->`if`(isprime(n) and isprime(2*n+7), n, NULL): seq(A023206(n), n=1..3*1000); # Wesley Ivan Hurt, Sep 07 2016

Mathematica

Select[Prime@Range@250, PrimeQ[2#+7]&] (* Vladimir Joseph Stephan Orlovsky, Apr 25 2011 *)

Prog

(Magma) [n: n in [0..1000] | IsPrime(n) and IsPrime(2*n+7)]; // Vincenzo Librandi, Nov 20 2010
(PARI) is(n)=isprime(2*n+7) && isprime(n) \\ Charles R Greathouse IV, Sep 07 2016

Crossrefs

Cf. A005384, A023204, A023205.

Sequence in context: A258039 A107438 A211204 * A359555 A049565 A094480

Adjacent sequences: A023203 A023204 A023205 * A023207 A023208 A023209

Keyword

nonn,easy

Author

David W. Wilson

Status

approved