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A023206 Numbers m such that m and 2*m + 7 both prime. 9
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 (list; graph; refs; listen; history; text; internal format)
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 * A049565 A094480 A215013

Adjacent sequences:  A023203 A023204 A023205 * A023207 A023208 A023209

KEYWORD

nonn,easy

AUTHOR

David W. Wilson

STATUS

approved

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Last modified October 23 16:46 EDT 2019. Contains 328373 sequences. (Running on oeis4.)