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A063909 Numbers n such that n and 2*n-5 are primes. 6
5, 11, 17, 23, 29, 47, 53, 59, 71, 89, 101, 131, 137, 149, 179, 197, 227, 233, 257, 263, 281, 311, 353, 383, 389, 401, 431, 443, 467, 479, 491, 509, 557, 593, 599, 617, 641, 647, 653, 683, 719, 743, 809, 821, 857, 863, 941, 947, 953, 977, 1109 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

All terms are == 5 mod 6. - Zak Seidov, Jan 07 2014

LINKS

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

FORMULA

Intersection of A089253 and A000040. - Michael B. Porter, Jan 07 2014

EXAMPLE

29 is in the sequence since n = 29 is prime, and 2n - 5 = 53 is also prime.

MATHEMATICA

Select[Prime[Range[500]], PrimeQ[2#-5]&] (* Harvey P. Dale, Oct 10 2011 *)

PROG

(PARI) { n=0; p=1; for (m=1, 10^9, p=nextprime(p+1); if (isprime(2*p - 5), write("b063909.txt", n++, " ", p); if (n==1000, break)) ) } \\ Harry J. Smith, Sep 02 2009

(MAGMA) [p: p in PrimesUpTo(2000) | IsPrime(2*p-5)]; // Vincenzo Librandi, Feb 25 2016

CROSSREFS

Subsequence of A016969.

Sequence in context: A144918 A144920 A051615 * A181575 A194384 A287305

Adjacent sequences:  A063906 A063907 A063908 * A063910 A063911 A063912

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Aug 31 2001

STATUS

approved

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Last modified August 24 03:51 EDT 2019. Contains 326260 sequences. (Running on oeis4.)