--- 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?

If you just want the factors, you can use Alpertron at

http://www.alpertron.com.ar/ECM.HTM
which knows about algebraic factors and knows about the tables of

known factors for numbers of this form. If you want to know how to

find the factors, you need to learn about algebraic factors and the

various factor lists. There is a discussion of Algebraic Factors in

the Cunningham Book, available online, and in the ElevenSmooth FAQ.

The needed factors are in Will Edgington's Mersenne factors lists

(2^n-1) and also Richard Brent's factor lists (a^n +/- 1 for a<10000

n<10000).