- -----Original Message-----

From: elevensmooth [mailto:elevensmooth@...]

Sent: 12 June 2007 22:57

To: primenumbers@yahoogroups.com

Subject: [PrimeNumbers] Re: Naive question on 2^1896-1

--- In primenumbers@yahoogroups.com, "Kevin" <research@...> wrote:

>

> I'm trying to factor the last part of 2^1896-1 or:

>

> 72009645598802661741572237135153453757864421072572019369424603012486080

> 97428061518078682794754267412326389601722982929011560986986540564455161

> 820809601187482593072913719887735073

> Do you just want the factors, or do you want to learn how to find the

> factors?

Hi,

The question arises from the results of a program I have that diverged from

the Wieferich search.

Basically it finds composite Mersenne numbers and a large composite or prime

(if you're lucky) that divides it.

A better example than the previous one is where the program output shows:

2869070461631637574244868351418889546260799144254581951743734382009219393441

76261145611475682317574468979232833614978133229351

divides 2^19071324012257094604424955-1

Which isn't much of a find since the above number actually divides 2^795-1.

So basically an hours running throws up a lot of large primes, it's just

unfortunate that nearly all already exist in lowM.txt or are trivially found

on Alpertron.

The premise is that it's very easy to produce thousands of large primes or

composites that divide a range of Mersenne numbers. What isn't easy is to

find a prime that isn't already known. Rather than attempt to factor a

specific number it produces a number that it knows will factor some Mersenne

number.

Still, I'll spend a while tuning the program and see if anything new pops

up.

Kevin. - Hello,

I have found in few seconds with my program:

2^1896 have prime factor 201487636602438195784363

I don't know, this factor are known ?

regards

__________________________________________________

Do You Yahoo!?

Sie sind Spam leid? Yahoo! Mail verfügt über einen herausragenden Schutz gegen Massenmails.

http://mail.yahoo.com - --- In primenumbers@yahoogroups.com, "N.L." <nluhn@...> wrote:

> 2^1896 have prime factor 201487636602438195784363

All factors of 2^1896-1 are known. The simplest way to check that is

>

> I don't know, this factor are known ?

to use the Alpertron Java factoring applet at

http://www.alpertron.com.ar/ECM.HTM

William

Poohbah of OddPerfect.org