A152843 Numbers n such that both 2n+3 and 4n+7 are prime.

0, 1, 4, 10, 13, 19, 25, 40, 43, 55, 64, 85, 88, 94, 115, 118, 124, 139, 145, 178, 208, 214, 220, 244, 253, 295, 319, 325, 328, 340, 358, 370, 379, 403, 454, 475, 505, 508, 514, 523, 550, 610, 613, 643, 703, 718, 724, 739, 748, 754, 778, 790, 799, 865, 904, 943

Offset: 1

Author

Vincenzo Librandi, Dec 14 2008

Keywords

• nonn
• easy

Comments

Or, numbers n such that 2n+3 is a Sophie Germain prime. [Klaus Brockhaus, Dec 22 2008]

Examples

			For n = 10, 2*n+3 = 23 is prime and 4*n+7 = 47 is prime. 23 = A005384(5).
		

Links

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

Crossrefs

Cf. A067076 (2n+3 is prime), A089986 (4n+7 is prime), A005384 (Sophie Germain primes).

Programs

Magma

[ n: n in [0..1000] | IsPrime(2*n+3) and IsPrime(4*n+7) ];

Mathematica

Join[{0}, Select[Range[1000], PrimeQ[2*#+3] && PrimeQ[4*#+7] &]] (* Vincenzo Librandi, Aug 30 2012 *)
Select[Range[0,1000],AllTrue[{2#+3,4#+7},PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Aug 07 2015 *)

Extensions

Edited and extended by Klaus Brockhaus, Dec 22 2008