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Old 2006-01-16, 11:31   #133
alpertron
 
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I completed the 15-digit level for M(30,402,457)-2 and Prime95 only found the product of the three prime factors shown above.
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Old 2006-01-26, 18:49   #134
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Up to now: 8108 curves with B1 = 11000000 for 2^4253 - 3.
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Old 2006-03-15, 13:40   #135
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On March 1st, the computer finished the 10600th curve for 2^4253 - 3, so the 45-digit level is completed for this number. There was no factor found.
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Old 2006-09-11, 21:53   #136
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2^32582657 -3 is divisible by 23 and 523657 (and no other prime < 5000000)

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Old 2006-09-20, 05:16   #137
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Quote:
Originally Posted by cyrix View Post
2^32582657 -3 is divisible by 23 and 523657 (and no other prime < 5000000)

Cyrix
5918466629 is also a factor. No other factors below 10^{10}.

Last fiddled with by ATH on 2006-09-20 at 05:17
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Old 2008-10-08, 06:56   #138
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2^43112609-3 has a factor: 191
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Old 2008-10-08, 07:15   #139
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2^37156667-3 has factors:

5
859
549001
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Old 2008-10-08, 18:07   #140
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Quote:
Originally Posted by jrk View Post
2^37156667-3 has factors:

5
859
549001
That should be

5^2
859
549001
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Old 2008-10-09, 00:42   #141
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2^37156667-3 = 5^2 * 859 * 549001 * 2201107 * ...

(and that's just 17 seconds of Pari/GP!)

Last fiddled with by CRGreathouse on 2008-10-09 at 00:55
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Old 2010-04-30, 16:40   #142
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Quote:
Originally Posted by ;1373
Hi. All this is pretty new to me and my maths is weak so forgive me if this is a daft question.

What are the chances that M39 (or one of the others) is the lower half of a twin prime? ie. M39 + 2 is also prime. Is it even possible?
Wait, you ask if M39+2, M39 and M39-2 can be primes? (3 primes with 2 as a gap between them)..
First, there cannot be such primes (3 primes with gap 2 between them).
Secondly, a merssene number and a number of the form (2^n+1) cannot be twin primes.
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Old 2010-04-30, 17:26   #143
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Quote:
Originally Posted by blob100 View Post
Secondly, a merssene number and a number of the form (2^n+1) cannot be twin primes.
Sure? Try 2^n-1 and 2^n+1 with n=2! What do you get?
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