mersenneforum.org Beginning driver/downdriver questions
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2011-08-15, 11:57   #1
biwema

Mar 2004

38110 Posts
Beginning driver/downdriver questions

Quote:
 Originally Posted by Andi47 There is a need to worry - it killed the downdriver.
[Having a closer look into the factordb]

Oh. I see. My fault.
I always thought only a 2 * p could be dangerous. Now learned something.

At least there is still hope to get back the downdriver from 2^2 * p.

Last fiddled with by schickel on 2011-08-22 at 20:43 Reason: Stupid fingers made typo in title...

 2011-08-15, 19:40 #2 henryzz Just call me Henry     "David" Sep 2007 Cambridge (GMT/BST) 2·5·587 Posts Is it always possible to gain the downdriver within 3 iterations from any driver? Maybe 4 iterations?
2011-08-22, 05:49   #3
JohnFullspeed

May 2011
France

7×23 Posts
What???

Quote:
 Originally Posted by henryzz Is it always possible to gain the downdriver within 3 iterations from any driver? Maybe 4 iterations?
I dont know what you call a ''DRIVER" and a downdriver
Is someone can explain...

Merci
John

 2011-08-22, 06:08 #4 firejuggler     Apr 2010 Over the rainbow 22×641 Posts a driver is something you find from one iteration to another, like 2^2*7, 2*3 and make the sequence grow. In some case, when the decomposition of the composite is 2* large integer, the sigma of the number is smaller than him., driving the sequence lower and lower, so it is a downdriver.
2011-08-22, 06:12   #5
schickel

"Frank <^>"
Dec 2004
CDP Janesville

2·1,061 Posts

Quote:
 Originally Posted by JohnFullspeed I dont know what you call a ''DRIVER" and a downdriver Is someone can explain... Merci John
Drivers are defined in an article in Mathematics of Computation in 1975 by Richard K Guy and John Selfridge. You can find the article free of charge here. There is a later article clarifying the proof. That one is available here.

(Thanks to the American Mathematical Society who has made its older articles available free of change.)

 2011-08-22, 11:01 #6 JohnFullspeed   May 2011 France 7·23 Posts Thanks for the link Perhaps you have a option but where? In a PDF file like here.you have a zoom (I read only size 26) but when you print the doc the police is the original siize(10,12...) Why? PDF is well a Print Format Like Millions of humans I am neer blind Adobbe forget us? John
2011-08-22, 20:41   #7
schickel

"Frank <^>"
Dec 2004
CDP Janesville

2·1,061 Posts

Quote:
 Originally Posted by JohnFullspeed Perhaps you have a option but where? In a PDF file like here.you have a zoom (I read only size 26) but when you print the doc the police is the original siize(10,12...) Why? PDF is well a Print Format Like Millions of humans I am neer blind Adobbe forget us? John
Unfortunate, but true. PDF tries to recreate the represented document exactly, which means it's hard to resize something after it's initially printed.

Try the attached. I upsized the text. (I was reluctant to post the driver article because of the nature of the release I got, but since it is freely available on ams.org now, I think this is a little more allowed...)

Be aware: without some more work some of the equations don't fit the page correctly, with the text overflowing off the right margin, but the main article text should be easier to manage.
Attached Files
 LargeDrives.pdf (215.1 KB, 154 views)

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