mersenneforum.org Predict "M51" (discussion)
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2018-01-02, 07:36   #12
Uncwilly
6809 > 6502

"""""""""""""""""""
Aug 2003
101×103 Posts

175528 Posts

Quote:
 Originally Posted by gophne Sagemath returns "123456791" as being a prime, and Prime95 is currently running on my machine with this number.
Quote:
 Originally Posted by George M Ooohhhhhh...... you mean 2^1233333331 - 1 is composite..... ahhh k
Quote:
 Originally Posted by gophne Running SAGEMATH code; %time factor(1233333331) returns that input as "prime"
Both 2^123456791-1 and 2^1233333331-1 have known factors. Thus, by rule 4, are not suitable guesses. For further inquires about the how, where, when, and why of this, please use a different thread. Also, why Prime95 is running on an exponent with a known factor, inquire in a different thread.

Both of your blind ignorance and insistence on being right is starting to feel like spam.

 2018-01-02, 08:27 #13 George M   Dec 2017 2×52 Posts My Second Guess 982451707 If anyone is struggling to come up with a prime (for any reason) then you can head below: http://www.primos.mat.br/2T_en.html :)
2018-01-02, 08:42   #14
GP2

Sep 2003

50228 Posts

Quote:
 Originally Posted by gophne Sagemath returns "123456791" as being a prime, and Prime95 is currently running on my machine with this number.

Quote:
 Originally Posted by ET_ The Mersenne you should test is 2^1233333331 - 1
The number 1,233,333,331 is indeed a prime number but 21,233,333,331−1 has a known factor, although you have to go to Mersenne.ca to see that, because such large numbers beyond 1 billion are beyond present capability for LL testing, and are not recorded by Primenet.

Last fiddled with by GP2 on 2018-01-02 at 08:45

2018-01-02, 08:49   #15
George M

Dec 2017

2×52 Posts

Quote:
 Originally Posted by GP2 Click here: 123456791, and then stop your machine. The number 1,233,333,331 is indeed a prime number but 21,233,333,331−1 has a known factor, although you have to go to Mersenne.ca to see that, because such large numbers beyond 1 billion are beyond present capability for LL testing, and are not recorded by Primenet.
I only chose that prime number because of all the 3’s in it haha

2018-01-02, 08:53   #16
GP2

Sep 2003

A1216 Posts

Quote:
 Originally Posted by George M 982451707
First of all, 982,451,707 is a prime number, but 2982,451,707−1 has a factor, click here

Secondly, take a look at this list of known Mersenne primes, and consider how improbable it is that there would be a gap with no Mersenne primes from roughly 70+ million to nearly 1 billion.

Try a little harder to make reasonable guesses.

2018-01-02, 08:55   #17
gophne

Feb 2017

101001012 Posts

Quote:
 Originally Posted by GP2 Click here: 123456791, and then stop your machine. The number 1,233,333,331 is indeed a prime number but 21,233,333,331−1 has a known factor, although you have to go to Mersenne.ca to see that, because such large numbers beyond 1 billion are beyond present capability for LL testing, and are not recorded by Primenet.
Hi GP2

I see what Uncwilly was saying now as well.

I will stop the current Prime95 process on my computer.

Regards

Last fiddled with by gophne on 2018-01-02 at 08:57

 2018-01-02, 09:20 #18 George M   Dec 2017 2·52 Posts Prime numbers not to pick First of all, I will try and pick a number that is greater than a billion so they are reasonable (perhaps I should put my previous guesses in the PREDICT M50 thread). I will have my final guess at the end of this post. Now, here are prime numbers $p$ that should not be picked if $p \ \in \ [74243591, \ 74243681]$ or $p \ \in \ [74294611, \ 74294861]$ Also, after looking at the 46th and 47th mersenne prime and the gap between both exponents, I consider my previous guess reasonable, but it doesn’t mean anything if M_n is factored, my previous guess being equal to n. So anyway, my final guess is..... Hmmm.... $1824261419$ Last fiddled with by George M on 2018-01-02 at 09:29
2018-01-02, 09:39   #19
ET_
Banned

"Luigi"
Aug 2002
Team Italia

72×97 Posts

Quote:
 Originally Posted by George M First of all, I will try and pick a number that is greater than a billion so they are reasonable (perhaps I should put my previous guesses in the PREDICT M50 thread). I will have my final guess at the end of this post. Now, here are prime numbers $p$ that should not be picked if $p \ \in \ [74243591, \ 74243681]$ or $p \ \in \ [74294611, \ 74294861]$ Also, after looking at the 46th and 47th mersenne prime and the gap between both exponents, I consider my previous guess reasonable, but it doesn’t mean anything if M_n is factored, my previous guess being equal to n. So anyway, my final guess is..... Hmmm.... $1824261419$
1824261419 has a factor

Last fiddled with by ET_ on 2018-01-02 at 09:40

2018-01-02, 09:43   #20
George M

Dec 2017

2·52 Posts

Quote:
 Originally Posted by ET_ 1824261419 has a factor
Man this is difficult...

Oh, and by the way, perhaps we should put a constraint on our guesses, such that our guesses should be less than 2^32 = 4294967296

………

It seems like 2^2252945257 - 1 may be prime. It has a probability of 63.7945% of being prime!! We also have another mersenne number with the exact probability: 2^2685457421 - 1. Funny that.

Last fiddled with by George M on 2018-01-02 at 10:06 Reason: Should be less than 2^32 because otherwise mersenne.ca can’t compute it

 2018-01-02, 09:46 #21 Batalov     "Serge" Mar 2008 Phi(3,3^1118781+1)/3 902810 Posts
2018-01-02, 09:53   #22
George M

Dec 2017

2×52 Posts

Quote:
 Originally Posted by Batalov
Who ever said otherwise? XD

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