[seqfan] Re: when is 1234...n a prime?

Ron Hardin rhhardin at att.net
Sat Oct 3 18:49:21 CEST 2015


I'm just curious, without knowing anything about it, if there's a better base than 10 for such removals.  I mean, why should 10 be the most efficient? rhhardin at mindspring.com rhhardin at att.net (either)
 
      From: eli Mcfly <elijaffe173 at gmail.com>
 To: Sequence Fanatics Discussion list <seqfan at list.seqfan.eu> 
 Sent: Saturday, October 3, 2015 11:50 AM
 Subject: [seqfan] Re: when is 1234...n a prime?
   
Has anyone taken care to remove numbers that end in 2,4,5,6,8,and 9 from
the testing algorithm? Some code could speed up the search.
Numbers that end in 9 are removed because 123456789*100000001000000001...
Will always end in nine.
Elias Jaffe
Just a brief update -- there are no primes among first 77,000 terms.

Regards,
Max

   


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