A143912 - OEIS

%I #6 Nov 21 2013 12:49:25

%S 2,23,113,191,233,443,593,1031,1409,2129,2399,2543,4349,4481,4919,

%T 5231,5399,6263,6329,6449,7541,10253,10613,11321,12101,13463,13553,

%U 13763,14009,15773,15923,17333,17939,18233,18341,18461,18803,19559,19661

%N Primes of the form : 2*p+1=p1(prime), 2*p1+3=p2(prime), 2*p2+5=p3(prime).

%C Subset of A005384. [From _R. J. Mathar_, Sep 05 2008]

%H Harvey P. Dale, <a href="/A143912/b143912.txt">Table of n, a(n) for n = 2..1000</a>

%e (prime)2*2+1=5(prime), 2*5+3=13(prime), 2*13+5=31(prime).

%t lst={};Do[p=Prime[n];If[PrimeQ[p1=2*p+1]&&PrimeQ[p2=2*p1+3]&&PrimeQ[p3=2*p2+5],AppendTo[lst,p]],{n,10^4}];lst

%t pfQ[n_]:=Module[{p1=2n+1,p2},p2=2p1+3;And@@PrimeQ[{p1,p2,2p2+5}]]; Select[Prime[ Range[2300]],pfQ] (* _Harvey P. Dale_, Nov 03 2011 *)

%K nonn

%O 2,1

%A _Vladimir Joseph Stephan Orlovsky_, Sep 04 2008