From: Bob Silverman <bobs@rsa.com>
Subject: Re: a problem about primes
Date: Mon, 03 Jan 2000 21:22:58 GMT
Newsgroups: sci.math
Summary: Which repunits are known prime?

In article <NG3c4.2204$wv4.272539@den-news1.rmi.net>,
  Kurt Foster <kfoster@rmi.net> wrote:
> In <84q1r1$1qj$1@nnrp1.deja.com>, hero_no_1@my-deja.com said:
> . Is the set of all primes for which (10^p-1)/9 is a prime known ?
>
>   Nobody knows.  The values p = 2, 19, 23, 317 and one other somewhat over
> 1,000 are known.  I'm not sure how far beyond that the exponents have been
> tested.

It is prime for p = 1031  and a probable prime for p = 49081.

There are no others for p < 50K

--
Bob Silverman
"You can lead a horse's ass to knowledge, but you can't make him think"


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