[seqfan] Re: A162302 (sigma divisibility) incomplete ?
Donald Alan Morrison
donmorrison at gmail.com
Wed Aug 25 00:49:53 CEST 2010
Richard,
I also get your result, but I am new, so take that with a grain of salt please:
%time
lst =[x for x in xrange(1,10^4+1) if float((sigma(x)+28)/x) ==
int((sigma(x)+28)/x)]; len(lst)
14
CPU time: 6.35 s, Wall time: 7.44 s
lst
[1, 28, 29, 62, 84, 182, 230, 252, 344, 756, 944, 2268, 6710, 6804]
Cheers,
Don
On Tue, Aug 24, 2010 at 3:01 PM, Richard Mathar
<mathar at strw.leidenuniv.nl> wrote:
>
> It seems that
> http://oeis.org/classic/A162302 is incomplete. I get
> 1,
> 28,
> 29,
> 62,
> 84,
> 182,
> 230,
> 252,
> 344,
> 756,
> 944,
> 2268,
> 6710,
> 6804,
> ....
> or is there something missing in the defn?
> Should this simply be replaced by 28*3^n, comments removed?
> Richard Mathar
>
> for n from 1 to 20000 do
> if (numtheory[sigma](n)+28) mod n = 0 then
> printf("%d,\n",n) ;
> end if;
> end do:
>
>
>
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