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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 STATUS approved

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