From: "Carl Johan Ragnarsson" Subject: Re: Sieve of John Horton Conway Date: Sat, 06 May 2000 21:49:49 GMT Newsgroups: sci.math It's very easy... Take the rational numbers 17/91, 78/85, 19/51, 23/38, 29/33, 77/29, 95/23, 77/19, 1/17, 11/13, 13/11, 15/14, 15/2, 55/1 Start with x(1)=2 and let x(n+1)=x(n)*(first number in list so result is integer). 2^p will appear in the list exactly for prime p, and in order! If you like more information, and don't have the article, I happened to get it at math club 3 days ago, so I can help you if you like to know more. /cjr