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A063910 Numbers n such that n and 2n-7 are primes. 3
5, 7, 13, 19, 37, 43, 67, 73, 79, 103, 109, 139, 157, 193, 223, 277, 307, 313, 349, 367, 373, 379, 397, 409, 433, 457, 463, 487, 499, 523, 547, 619, 643, 727, 733, 739, 769, 787, 853, 877, 883, 919, 937, 997, 1009, 1069, 1093, 1123, 1129, 1237 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

All terms > 5 are == 1 (mod 6). - Zak Seidov, Jan 07 2014

LINKS

Harry J. Smith, Table of n, a(n) for n = 1..1000

FORMULA

A089192 INTERSECT A000040. - R. J. Mathar, Mar 23 2017

MATHEMATICA

Select[Prime[Range[2, 2000]], PrimeQ[2 # - 7]&] (* Vincenzo Librandi, Feb 02 2014 *)

PROG

(PARI) { n=0; p=1; for (m=1, 10^9, p=nextprime(p+1); if (isprime(2*p - 7), write("b063910.txt", n++, " ", p); if (n==1000, break)) ) } \\ Harry J. Smith, Sep 02 2009

(MAGMA) [n: n in [3..2000] | IsPrime(n) and IsPrime(2*n-7)]; // Vincenzo Librandi, Feb 02 2014

CROSSREFS

Sequence in context: A297674 A072677 A117249 * A288632 A189557 A045444

Adjacent sequences:  A063907 A063908 A063909 * A063911 A063912 A063913

KEYWORD

easy,nonn

AUTHOR

N. J. A. Sloane, Aug 31 2001

STATUS

approved

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Last modified August 23 00:59 EDT 2019. Contains 326211 sequences. (Running on oeis4.)