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

Hugo Pfoertner yae9911 at gmail.com
Fri Sep 22 21:43:01 CEST 2017


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/
>>
>
>


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