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Old 2004-02-27, 03:39   #1
illman-q
 
Feb 2004
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Lightbulb The 40th known Mersenne prime, 220996011-1 is not PRIME!

Hello I am very new to this but to a person that is no mathamatician, when I look at the short representation of the large Mersenne Prime, I see a -1 at the end. Now if thats what you have to do to the actually number, subtract 1 to make it a prime them the above mentioned number is NOT A PRIME. I am probably illinformed and wrong with the calculations but thats what I did and then divided it with a certain number and found it to be divisible by it. Can anyone please enlighten me of what is right or wrong?

I told you i was very new!(hehehahah)
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Old 2004-02-27, 07:58   #2
outlnder
 
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The actual number is 2 to the 20996011 power minus 1.
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Old 2004-02-27, 15:09   #3
Uncwilly
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Yes, it is (220996011)-1 which is about 6.5 million digits long. The number is not 220996011-1 (which is even), nor is it (2 X 20996011)-1, nor even 220996011-1.
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Old 2004-02-28, 04:17   #4
illman-q
 
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Default NO JOKE

Quote:
Originally Posted by Uncwilly
Yes, it is (220996011)-1 which is about 6.5 million digits long. The number is not 220996011-1 (which is even), nor is it (2 X 20996011)-1, nor even 220996011-1.
NO JOKE its over 6 million digits. I downloaded the 6 million+ digits and thats what was subtracted by 1 and got a multiple of a certian number that I used.

Last fiddled with by illman-q on 2004-02-28 at 04:20
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Old 2004-02-28, 05:07   #5
dave_0273
 
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Well, then - what is the factor????
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Old 2004-02-28, 05:13   #6
nfortino
 
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Quote:
Originally Posted by illman-q
NO JOKE its over 6 million digits. I downloaded the 6 million+ digits and thats what was subtracted by 1 and got a multiple of a certian number that I used.
Is this to say you to the 6 million digit file, and subtracted 1, and found factors of that number? If so, then you were factoring 2^20966011-2, which has many factors (one of them being 2). The file you downloaded already has the -1 in it, so you can't subtract one again.
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Old 2004-02-28, 08:44   #7
Pablo the Duck
 
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Quote:
Originally Posted by dave_0273
Well, then - what is the factor????
I reckon his "factor" is 2.
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Old 2004-02-28, 22:07   #8
Maybeso
 
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Quote:
Originally Posted by nfortino
...If so, then you were factoring 2^20966011-2, which has many factors (one of them being 2). The file you downloaded already has the -1 in it, so you can't subtract one again.
2^20966011-2 = 2(2^20966010-1), 20966010 = 2*3*5*13*53759 -->
= 2(2^10483005-1)(2^10483005+1)
= 2(2^3494335-1)(2^6988670 + 2^3494335 + 1)(2^3494335+1)(2^6988670 - 2^3494335 + 1)
= ...

hmm, my binomial expansion skills are a bit rusty ... anyway, his factor is in there, but I vote for '2' as well.
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Old 2004-02-29, 19:32   #9
ixfd64
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Sounds like fame-bait to me...
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Old 2004-03-02, 02:50   #10
illman-q
 
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Talking The fctor is 19 no Fame seeking factor!

Quote:
Originally Posted by ixfd64
Sounds like fame-bait to me...
Not an actor a factor of 19!

Last fiddled with by illman-q on 2004-03-02 at 03:00
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Old 2004-03-04, 02:26   #11
ixfd64
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Oops, meant to say "flame-bait"...

Last fiddled with by ixfd64 on 2004-03-04 at 02:27
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