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-   -   How long before you found your first composite number? (https://www.mersenneforum.org/showthread.php?t=2906)

Bundu 2004-08-13 19:21

How long before you found your first composite number?
 
Hey Guys,

Hope this is the right thread! How long was it before your first composite number on any test? I have a number of tests running and I haven't found a single composite number yet (I've been on the search for 5 months)!

I was wondering if I had hit a "rich vein" of exponents that might yield something nice or if this was an everyday occurence? Any comments??

Cheers, Mark

dsouza123 2004-08-13 21:13

The first one, I don't know but in the past 11.5 months I've found 17 factors
doing TF (Trial Factoring) 24/7 so on average 1 every 20 (24h) days using two PC's
so about 1 every 40 days for one PC. 1 Ghz PCs

If you do LL (Lucas-Lehmer first time tests) then very nearly every time
you send in a result it is a composite, just don't know the factors,
only the extremely rare ones are Mersenne primes.

ET_ 2004-08-14 11:26

[QUOTE=Bundu]Hey Guys,

Hope this is the right thread! How long was it before your first composite number on any test? I have a number of tests running and I haven't found a single composite number yet (I've been on the search for 5 months)!

I was wondering if I had hit a "rich vein" of exponents that might yield something nice or if this was an everyday occurence? Any comments??

Cheers, Mark[/QUOTE]

If you are doing P-1 or ECM tests, the probability of finding a factor is also related to the amount of RAM you have.

Luigi

dave_0273 2004-08-14 12:21

Bundu: I am a little confused by what you have said.

[QUOTE=Bundu]I have a number of tests running and I haven't found a single composite number yet (I've been on the search for 5 months)![/QUOTE]

What do you mean exactly??

1) You just finished your first LL test after 5 months or
2) You have been factoring for 5 months but have not yet found a factor. Therefore have been unable to prove that any of the numbers that you have been tested to be composite or prime.

or I am completly off on the wrong track?

I am assuming that you are working for GIMPS?? Am I right??


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