[seqfan] Re: Primes where every other digit is 1

David Sycamore djsycamore at yahoo.co.uk
Sun Oct 24 00:20:33 CEST 2021


Every other digit in the concatenation of the first n terms is 1: (ie 1 at every 2k-th place).

11,31,41,61,71,113,131,211,1013,1019, 10111,11113,11131…..

Includes  primes with 1s at places we are not (primarily) interested in.

Any use? 

Regards

David. 

> On 23 Oct 2021, at 02:52, zak seidov via SeqFan <seqfan at list.seqfan.eu> wrote:
> 
>  11?
> On Friday, October 22, 2021, 08:56:31 AM GMT+3, Neil Sloane <njasloane at gmail.com> wrote:  
> 
> This 31,41,61,71,101,131,151,181,191,2131,2141 seems interesting - and it
> makes a good puzzle, so yes, please submit it!
> 
> Best regards
> Neil
> 
> Neil J. A. Sloane, Chairman, OEIS Foundation.
> 11 South Adelaide Avenue, Highland Park, NJ 08904, USA.
> Also Visiting Scientist, Math. Dept., Rutgers University, Piscataway, NJ.
> Phone: 732 828 6098; home page: http://NeilSloane.com
> Email: njasloane at gmail.com
> 
> 
> 
>> On Thu, Oct 21, 2021 at 8:59 PM Lars Blomberg <lars.blomberg2 at hotmail.com>
>> wrote:
>> Hello,
>> Is this of interest:
>> 31,41,61,71,101,131,151,181,191,2131,2141, ...
>> ?
>> ... or 3,7,9.
>> /Lars Blomberg
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>> Seqfan Mailing list - http://list.seqfan.eu/
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