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Re: factor



I'm responding to the list as well as by email, to demonstrate the
useful FactorIntegerECM. The calc below took a few minutes.
FactorInteger had been running for several hours without output when I
stopped it.

-David.

In[1]:= <<NumberTheory`FactorIntegerECM`

In[2]:= FactorIntegerECM[ (10^79-1) / 9 ]

Out[2]= 6172891015272307

In[3]:= ( (10^79-1) / 9 ) / %

Out[3]= 179998498007192867978127821006182312868256693827421272815886173


William Moppett wrote:
> 
> help
> can anyone give me a factor of (10^71 - 1)/9 Mathematica 3.0 says it is
> not prime email
> wmoppet@nsw.bigpond.net.au

-- 
David Pearson,              Phone: +44 (0)118  9318741 ESSC,            
Fax:   +44 (0)118  9316413  University of Reading,
Reading RG6 6AL,            Email: dwcp@mail.nerc-essc.ac.uk UK.



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