The 40th known Mersenne prime, 220996011-1 is not PRIME!

illman-q · 2004-02-27, 03:39

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)

outlnder · 2004-02-27, 07:58

The actual number is 2 to the 20996011 power minus 1.

Uncwilly · 2004-02-27, 15:09

Yes, it is (2^20996011)-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 2^20996011-1.

illman-q · 2004-02-28, 04:17

Quote:

Originally Posted by Uncwilly

Yes, it is (2^20996011)-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 2^20996011-1.

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.

dave_0273 · 2004-02-28, 05:07

Well, then - what is the factor????

nfortino · 2004-02-28, 05:13

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.

Pablo the Duck · 2004-02-28, 08:44

Quote:

Originally Posted by dave_0273

Well, then - what is the factor????

I reckon his "factor" is 2.

Maybeso · 2004-02-28, 22:07

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.

ixfd64 · 2004-02-29, 19:32

Sounds like fame-bait to me...

illman-q · 2004-03-02, 02:50

Quote:

Originally Posted by ixfd64

Sounds like fame-bait to me...

Not an actor a factor of 19!

ixfd64 · 2004-03-04, 02:26

Oops, meant to say "flame-bait"...

2004-02-27, 03:39	#1
illman-q Feb 2004 Sydney 7 Posts	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)

2004-03-04, 02:26	#11
ixfd64 Bemusing Prompter "Danny" Dec 2002 California 100110111111₂ Posts	Oops, meant to say "flame-bait"... Last fiddled with by ixfd64 on 2004-03-04 at 02:27

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2004-02-27, 07:58	#2
outlnder Aug 2002 2·3·53 Posts	The actual number is 2 to the 20996011 power minus 1.

2004-02-27, 15:09	#3
Uncwilly 6809 > 6502 """"""""""""""""""" Aug 2003 101×103 Posts 2⁴×3×227 Posts	Yes, it is (2^20996011)-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 2^20996011-1.

2004-02-28, 05:07	#5
dave_0273 Oct 2003 Australia, Brisbane 2×5×47 Posts	Well, then - what is the factor????

2004-02-29, 19:32	#9
ixfd64 Bemusing Prompter "Danny" Dec 2002 California 5×499 Posts	Sounds like fame-bait to me...