I don't think this is known. The only doubtful case would be p=3, which is easily confirmed. The usual probability arguments say that there will be an infinite number of q, and they aren't exactly rare. AFAIK, the simpler question of whether P and 2P+1 are both prime infinitely often is still open. Rich -----Original Message----- From: math-fun-bounces+rschroe=sandia.gov@mailman.xmission.com [mailto:math-fun-bounces+rschroe=sandia.gov@mailman.xmission.com] On Behalf Of Daniel Asimov Sent: Tuesday, January 09, 2007 7:51 AM To: math-fun@mailman.xmission.com Subject: [math-fun] CORRECTION Re: Question about primes MAKE THAT INSTEAD: Is it known whether for each odd prime p there exists at least one odd prime q such that pq + 2 is prime? --Dan _______________________________________________ math-fun mailing list math-fun@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/math-fun