A129119 Numbers of the form 2*p (with p a prime number) such that p^2+4 is prime.

6, 10, 14, 26, 34, 74, 94, 134, 146, 194, 206, 274, 326, 334, 386, 466, 554, 586, 614, 626, 634, 694, 746, 926, 974, 1006, 1094, 1154, 1186, 1214, 1226, 1354, 1486, 1574, 1646, 1654, 1706, 1766, 1906, 1934, 1966, 1994, 2174, 2234, 2246, 2474, 2734, 2846

Offset: 1

Author

Giovanni Teofilatto, May 25 2007

Keywords

• easy
• nonn

Examples

			7^2 + 4 = 53 which is a prime number. Therefore 2*7 is in the sequence.
		

Crossrefs

Cf. A045637, A062324.

Programs

Mathematica

2*Select[Prime@Range[250], PrimeQ[ #^2 + 4] &] (* Ray Chandler, May 27 2007 *)
a={};For[n=1,n<300,n++,If[PrimeQ[Prime[n]^2 + 4], AppendTo[a, 2*Prime[n]]]]; a (* Stefan Steinerberger, May 27 2007 *)

Formula

a(n) = 2*A062324(n).

Extensions

Extended and edited by Ray Chandler and Stefan Steinerberger, May 27 2007