[seqfan] Fwd: A nice (decimal) property of 78
Maximilian Hasler
maximilian.hasler at gmail.com
Mon Oct 27 15:34:42 CET 2008
(10:05) gp > for(i=11,9999,i%10|next;eulerphi(i)==eulerphi(i\10)*eulerphi(i%10)&print1(i","))
78,897,918,2598,4758,7917,8217,
Maximilian
PS: can one have eulerphi(i)=product(eulerphi( k-th digit of i )) for i>78 ?
I don't think so; it seems as if there would be strict ">" for all i
different from 78.
On Mon, Oct 27, 2008 at 05:01, Olivier Gerard <olivier.gerard at gmail.com> wrote:
> Message from Farideh Firoozbakht <mymontain at yahoo.com>
>
> Please put Farideh in copy of your answers today.
>
> Olivier
>
>
> ---------- Forwarded message ----------
>
> Dear seqfans,
>
> phi(78)=phi(7)*phi(8), does there exist another such number?
>
> Farideh
>
>
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