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A023204 Numbers k such that k and 2*k + 3 are both prime. 30
2, 5, 7, 13, 17, 19, 29, 43, 47, 53, 67, 73, 89, 97, 113, 127, 137, 139, 157, 167, 173, 193, 197, 199, 223, 227, 229, 269, 277, 283, 307, 337, 349, 353, 379, 383, 397, 409, 439, 463, 467, 487, 503, 509, 523, 547, 557, 563, 599, 607, 613, 617, 643, 647, 659, 739, 743, 773 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

FORMULA

A067076 INTERSECT A000040. - R. J. Mathar, Mar 23 2017

MAPLE

A023204 := proc (n) if isprime(n) and isprime(2*n+3) = true then n end if end proc; seq(A023204(n), n=1..1000); # Wesley Ivan Hurt, Jun 28 2014

MATHEMATICA

f[n_]:=PrimeQ[2*n+3]; lst={}; Do[p=Prime[n]; If[f[p], AppendTo[lst, p]], {n, 6!}]; lst (* Vladimir Joseph Stephan Orlovsky, Oct 03 2009 *)

Select[Prime[Range[200]], PrimeQ[2#+3]&] (* Harvey P. Dale, May 03 2012 *)

PROG

(MAGMA) [p: p in PrimesUpTo(1000) | IsPrime(2*p+3)]; // Vincenzo Librandi, Nov 20 2010

(PARI) is(n)=isprime(2*n+3)&&isprime(n) \\ Charles R Greathouse IV, Jul 02 2013

CROSSREFS

Cf. A089530, A089531, A089532.

Sequence in context: A069346 A023240 A291284 * A248606 A252801 A270617

Adjacent sequences:  A023201 A023202 A023203 * A023205 A023206 A023207

KEYWORD

nonn,easy

AUTHOR

David W. Wilson

STATUS

approved

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Last modified September 19 04:39 EDT 2019. Contains 327187 sequences. (Running on oeis4.)