[seqfan] Re: 647089

Emmanuel Vantieghem emmanuelvantieghem at gmail.com
Thu Nov 27 14:13:13 CET 2014


How can the odd number  2^(k-1) -1  be divisible by the even number
 k*(k-1) ?

Emmanuel.

2014-11-27 11:33 GMT+01:00 Olivier Gerard <olivier.gerard at gmail.com>:

> On Thu, Nov 27, 2014 at 10:45 AM, юрий герасимов <2stepan at rambler.ru>
> wrote:
>
> >
> > Dear SeqFans.
> >
> > MAGMA calculator can not find the second and subsequent values of
> > composites k such that k*(k - 1) divides 2^(k - 1) - 1. Help
> >
> > 647089, ... What in the ne[t one?
> >
> > Best regards, JSG
> > .
> >
>
> I don't think your formula is correct
>
> 2^647088 - 1  is not divisible by 647088   so it cannot be divisible by
> 647089*647088
>
> Olivier
>
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