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From: chuck@dartvax.UUCP (Chuck Simmons)
Newsgroups: net.math
Subject: Re: palindromic prime numbers -- a curious query
Message-ID: <2572@dartvax.UUCP>
Date: Thu, 15-Nov-84 08:20:41 EST
Article-I.D.: dartvax.2572
Posted: Thu Nov 15 08:20:41 1984
Date-Received: Sat, 17-Nov-84 07:57:23 EST
References: <3470@ecsvax.UUCP>
Organization: Dartmouth College, Hanover, NH
Lines: 15

> There weren't any 4-digit, 6-digit, or
> 8-digit palindromic primes.  Maybe he got beyond that, to 9- and/or 10-digit
> primes, because he got far enough, in any event, to arrive at a conjecture:
>
> Ziff's conjecture:  The number of digits in the decimal representation of a
> palindromic prime is itself prime.

Note that any palindromic number with an even number of digits is
divisible by 11, whether prime or not.

Ziff obviously didn't get to 9-digit primes.  I just asked our honeywell
to find me a 9-digit palindromic prime.  It liked the 4th one it looked
at:  100030001

dartvax!chuck