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From: gjk@talcott.UUCP (Greg J Kuperberg)
Newsgroups: net.math
Subject: Re: palindromic primes
Message-ID: <118@talcott.UUCP>
Date: Tue, 20-Nov-84 11:44:24 EST
Article-I.D.: talcott.118
Posted: Tue Nov 20 11:44:24 1984
Date-Received: Wed, 21-Nov-84 05:15:39 EST
References: <164@faron.UUCP>
Organization: Harvard
Lines: 12

> 
> 	Currently, the largest known palindromic prime is R1031, which
> 	is (10^1031-1)/9. It is a string of 1031 ones. It was just recently
> 	proved prime by Hugh Williams at the University of Manitoba. The
> 	proof utilised a recent factorization by Atkins and Rickert at 
> 	the Univerisity of Illinois of 10^103+1. It has been known to be
> 	a probable prime for quite some time. R317 is also prime.

Of course, if you're willing to be live in base 2, the 15 or so largest
known primes happen to all be palindromic.  They are also strings of ones.
How big is the highest one, folks?  I think it's somewhere around 2^130,000
(give or take a hundred orders of magnitude).