A130326 Least prime p such that 3*p*2^n+1 is prime.

2, 2, 3, 3, 2, 2, 3, 2, 19, 5, 5, 2, 5, 11, 3, 47, 7, 2, 11, 19, 47, 11, 11, 59, 97, 11, 23, 5, 11, 2, 31, 13, 37, 3, 53, 2, 71, 5, 5, 97, 2, 7, 3, 3, 5, 167, 41, 37, 5, 163, 23, 73, 31, 17, 59, 19, 29, 41, 73, 43, 59, 47, 71, 3, 109, 2, 11, 3, 79, 41, 13

Offset: 0

Author

Pierre CAMI, May 24 2007

Keywords

• nonn

Examples

			3*2*2^0+1=7 prime so for n=0 p=2
3*2*2^1+1=13 prime so for n=1 p=2
		

Links

• Pierre CAMI, Table of n, a(n) for n = 0..500

Crossrefs

Cf. A130325, A130327.

Programs

Mathematica

nn=100;Flatten[Module[{prs=Prime[Range[nn]],c},Table[c=2^n;Select[prs, PrimeQ[ 3c #+1]&,1],{n,0,nn}]]] (* Harvey P. Dale, Sep 01 2013 *)

Extensions

More terms from Harvey P. Dale, Sep 01 2013