A237810 Primes p such that 2*p+1 and 2*p+7 are also prime.

2, 3, 5, 11, 23, 41, 53, 83, 113, 131, 173, 191, 251, 281, 293, 593, 641, 683, 743, 953, 1031, 1103, 1451, 1481, 1601, 2003, 2063, 2141, 2393, 2693, 2903, 3023, 3413, 3593, 3623, 3761, 3821, 3911, 4211, 4373, 4481, 4733, 4871, 5081, 5303, 5441, 5741, 5903

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+7 = 29 are all prime.

Mathematica

Select[Prime[Range[10000]], PrimeQ[2 # + 1]&&PrimeQ[2 # + 7]&] (* Vincenzo Librandi, Feb 15 2014 *)

Prog

(PARI) s=[]; forprime(p=2, 10000, if(isprime(2*p+1) && isprime(2*p+7), s=concat(s, p))); s
(Magma) [p: p in PrimesUpTo(9200) | IsPrime(2*p+1) and IsPrime(2*p+7)]; // Vincenzo Librandi, Feb 15 2014

Crossrefs

Cf. A126107, A237811, A237812, A237813, A237814.

Sequence in context: A019405 A079848 A329749 * A073434 A109551 A326393

Adjacent sequences: A237807 A237808 A237809 * A237811 A237812 A237813

Keyword

nonn,easy

Author

Colin Barker, Feb 13 2014

Status

approved