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

%I #7 Sep 01 2013 11:37:10

%S 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,

%T 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,

%U 59,19,29,41,73,43,59,47,71,3,109,2,11,3,79,41,13

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

%H Pierre CAMI, <a href="/A130326/b130326.txt">Table of n, a(n) for n = 0..500</a>

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

%e 3*2*2^1+1=13 prime so for n=1 p=2

%t 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 *)

%Y Cf. A130325, A130327.

%K nonn

%O 0,1

%A _Pierre CAMI_, May 24 2007

%E More terms from _Harvey P. Dale_, Sep 01 2013

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