A237814 - OEIS

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A237814

Primes p such that 2*p+1 and 2*p+19 are also prime.

2, 5, 11, 41, 89, 131, 191, 251, 419, 431, 641, 809, 1031, 1229, 1409, 1439, 1511, 1559, 1601, 1889, 1901, 1931, 2069, 2351, 2399, 2459, 2699, 2741, 2819, 2939, 3359, 3449, 3491, 3761, 3779, 3911, 4409, 4919, 5081, 5849, 6131, 6449, 6491, 6551, 7079, 7151

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

EXAMPLE

11 is in the sequence because 11, 2*11+1 = 23 and 2*11+19 = 41 are all prime.

MATHEMATICA

Select[Prime[Range[8000]], PrimeQ[2 # + 1] && PrimeQ[2 # + 19] &] (* Vincenzo Librandi, Feb 15 2014 *)

PROG

(PARI) s=[]; forprime(p=2, 10000, if(isprime(2*p+1) && isprime(2*p+19), s=concat(s, p))); s

(Magma) [p: p in PrimesUpTo(8000) | IsPrime(2*p+1) and IsPrime(2*p+19)]; // Vincenzo Librandi, Feb 15 2014