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

Robert G. Wilson v rgwv at rgwv.com
Thu Oct 15 17:35:17 CEST 2015

```Seq. Fans,

While we have not found any terms in A007908 which are primes, such is not the case for A252043. A007908 is a subsequence of A252043.

I found 10, 14, 24, 235, 2804, 4347, …, . The search limit was 25000.

Bob.

-----Original Message-----
From: SeqFan [mailto:seqfan-bounces at list.seqfan.eu] On Behalf Of Max Alekseyev
Sent: Monday, October 12, 2015 12:03 AM
To: Sequence Fanatics Discussion list
Subject: [seqfan] Re: when is 1234...n a prime?

I've completed the search below 10^5 -- still no primes.
Max

On Sat, Oct 3, 2015 at 9:08 AM, Max Alekseyev <maxale at gmail.com> wrote:

> Just a brief update -- there are no primes among first 77,000 terms.
>
> Regards,
> Max
>
>
> On Tue, Sep 29, 2015 at 9:18 PM, Neil Sloane <njasloane at gmail.com> wrote:
> > To Seq Fans:
> >
> > Consider the sequence with nth term equal to the concatenation of
> > the decimal numbers 1234...n (https://oeis.org/A007908
> ).
> > When is the first prime? The comments in A007908 say that there
> > should be infinitely many primes, and that there are no primes among
> > the first 64000 terms.
> > If you would like to help with this search, you could leave a
> > comment in A007908 saying that there are no primes among terms X
> > through Y, or, of course, that n = Z gives a (probable) prime, which
> > would be pretty exciting.
> >
> >
> > Best regards
> > Neil
> >
> > Neil J. A. Sloane, President, OEIS Foundation.
> > 11 South Adelaide Avenue, Highland Park, NJ 08904, USA.
> > Also Visiting Scientist, Math. Dept., Rutgers University, Piscataway, NJ.
> > Email: njasloane at gmail.com
> >
> > _______________________________________________
> >
> > Seqfan Mailing list - http://list.seqfan.eu/
>

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