[seqfan] Re: Iteration of k -> sigma(k)-1

Neil Sloane njasloane at gmail.com
Fri Sep 22 21:46:34 CEST 2017


Hugo, that's great!  I've created A292115 for the records (under both our
names, hope that is OK)

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.
Phone: 732 828 6098; home page: http://NeilSloane.com
Email: njasloane at gmail.com


On Fri, Sep 22, 2017 at 3:43 PM, Hugo Pfoertner <yae9911 at gmail.com> wrote:

> I've found more records of A039655:
> 0, 2, 5, 6, 7, 11, 13, 15, 17, 21, 23, 24, 25, 26, 29, 40, 42, 44, 45, 46,
> 47, 54, 55, 56, 57, 58,
> 60, 64, 66, 72, 74
> This is definitely different from A073485.
>
> On Fri, Sep 22, 2017 at 8:53 PM, Hugo Pfoertner <yae9911 at gmail.com> wrote:
>
> > Neil, all,
> >
> > for A039655 an a-file of 1 million terms is available.
> >
> > The records of A039655 I've computed so far are
> > 0, 2, 5, 6, 7, 11, 13, 15, 17, 21, 23, 24, 25, 26, 29, 40, 42, 44, 45,
> 46,
> > 47, 54, 55, 56, 57, 58,
> >
> > A corresponding extension of A292114 is submitted.
> >
> > Hugo Pfoertner
> >
> >
> >
> > On Fri, Sep 22, 2017 at 3:10 PM, Neil Sloane <njasloane at gmail.com>
> wrote:
> >
> >> Dear Seq Fans,
> >> According to Richard Guy, Erdos conjectured that the trajectory of n
> under
> >> that map always reaches a prime. A039654 gives the prime reached, or -1
> (I
> >> changed the escape value to make it consistent with similar sequences),
> >> and A039655 gives no. of steps.
> >> I just created A292112 and -3 for the records in A039654. They need
> >> b-files.
> >> The record values in A039655 appear to match A073485, but surely that is
> >> just a coincidence, so could someone please compute more terms? The
> >> positions of the records in A039655 is the new A292114.
> >>
> >> In other words, the records in the present b-file for A039655 are [0, 2,
> >> 5,
> >> 6, 7, 11, 13, 15, 17] - how does this continue?
> >> The positions of the records are [2, 4, 9, 121, 301, 441, 468, 3171,
> 8373]
> >> which is now A292114. How does this continue, and what ARE these
> numbers?
> >>
> >> A039655 could use a bigger b-file, or an a-file with 100,000 or more
> >> terms.
> >>
> >> --
> >> Seqfan Mailing list - http://list.seqfan.eu/
> >>
> >
> >
>
> --
> Seqfan Mailing list - http://list.seqfan.eu/
>


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