-----Oprindelig meddelelse-----
Fra: Torben Schlüntz
Sendt: lø 23-03-2002 02:54
Til: Bruce Leenstra
Cc:
Emne: SV: Mersenne: Factors aren't just factors
Bruce Leenstra wrote:
>You'll notice that 'tempvalue == 1' is only the exit condition
for the loop above. This is because every prime is a factor of some
>mersenne number M(v) { plus the set of M(kv), which are all composite
}. Of course GIMPS is only interested in those where v >is prime. My
program will abort the loop and prompt me if count > (q-1)/2, indicating
q isn't a factor of any M(v). It hasn't >happened yet.
Yes I got it now, and with the same
multiply by 2 - take modulus of factor - check for 1 - check for
(q-1)/2 - repeat
just proved a low factor for M641 as well as the usual M29, 43
etc. :-)
And you're right - the algorithm tells - whenever a factor is
found, it will be factor again and again for other GIMPS uninteresting
composite M's, like 89 is a factor for M11 then M22 then M11*x. So there
is no SUPERfactor being a factor for several M's.
Last you say any prime will be a factor for some Mx, quite
interesting, and yes to pick one 641 is a factor of M64.
br tsc
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