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

1,3

Comments

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

Links

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

Example

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

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 *)

Prog

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

Crossrefs

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

Sequence in context: A310358 A143804 A342742 * A139121 A310359 A079932

Adjacent sequences: A152840 A152841 A152842 * A152844 A152845 A152846

Keyword

nonn,easy

Author

Vincenzo Librandi, Dec 14 2008

Extensions

Edited and extended by Klaus Brockhaus, Dec 22 2008

Status

approved