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

1,1

Links

Table of n, a(n) for n=1..48.

Formula

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

Example

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

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 *)

Crossrefs

Cf. A045637, A062324.

Sequence in context: A315238 A315239 A119623 * A259020 A259021 A171251

Adjacent sequences: A129116 A129117 A129118 * A129120 A129121 A129122

Keyword

easy,nonn

Author

Giovanni Teofilatto, May 25 2007

Extensions

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

Status

approved