mersenneforum.org Progress of n^41+/-1
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 2018-11-07, 10:51 #1 MisterBitcoin     "Nuri, the dragon :P" Jul 2016 Good old Germany 2×7×53 Posts Progress of n^41+/-1 I noticed that all number of the form n^41-1 with n<6600 are fully factored. The smallest n been unfactored is n=6697 with an C128 cofactor. I also noticed, that n^41+1 is much less factored, only up to n=1100 are all numbers FF. The smallest n been unfactored is n=1109 with C122 cofactor. Between n=1000 and n=1500 are all numbers FF. Going up to n=2000. I´ll at least pretest these numbers and list them here. From time to time I´ll take them down. Please note: Slow progress. Last fiddled with by MisterBitcoin on 2018-11-08 at 21:25 Reason: Updated progress
2018-11-07, 11:33   #2
axn

Jun 2003

471610 Posts

Quote:
 Originally Posted by MisterBitcoin I noticed that all number of the form n^41-1 with n<6600 are fully factored. The smallest n been unfactored is n=6697 with an C128 cofactor. I also noticed, that n^41+1 is much less factored, only up to n=1100 are all numbers FF. The smallest n been unfactored is n=1109 with C122 cofactor. Between n=1000 and n=1500 are 18 numbers not fully factored. I´ll at least pretest these numbers and list them here. Please note: Slow progress.
These are all SNFS numbers, so a quadcore could knock them all out in a couple of hours ?

2018-11-07, 13:25   #3
MisterBitcoin

"Nuri, the dragon :P"
Jul 2016
Good old Germany

2·7·53 Posts

Quote:
 Originally Posted by axn These are all SNFS numbers, so a quadcore could knock them all out in a couple of hours ?

All of my resources for factoring are used for FDB (90 dd up to 99 dd). When I´m done with that range I´m able to switch to something else.

For now I´m just pretesting with one core. That takes ~4 hours/canidate (at C125).

2018-11-07, 13:33   #4
axn

Jun 2003

22·32·131 Posts

Quote:
 Originally Posted by MisterBitcoin For now I´m just pretesting with one core. That takes ~4 hours/canidate (at C125).
4 hours or 4 minutes? 4 hours is way too much. Like I said, these are SNFS - actual SNFS will be much faster, I think.

2018-11-07, 13:48   #5
MisterBitcoin

"Nuri, the dragon :P"
Jul 2016
Good old Germany

2E616 Posts

Quote:
 Originally Posted by axn 4 hours or 4 minutes? 4 hours is way too much. Like I said, these are SNFS - actual SNFS will be much faster, I think.

ECM pretest takes ~4 hours.

The C122 took 50 minutes to complete, with 1 core. :)

Last fiddled with by MisterBitcoin on 2018-11-07 at 14:41

2018-11-07, 16:53   #6
VBCurtis

"Curtis"
Feb 2005
Riverside, CA

112E16 Posts

Quote:
 Originally Posted by MisterBitcoin ECM pretest takes ~4 hours. The C122 took 50 minutes to complete, with 1 core. :)
Why would you spend 5 times the SNFS factoring time on ECM? What polynomial are you using for SNFS? Something like 100 curves at B1=50k is enough.

2018-11-07, 18:29   #7
Batalov

"Serge"
Mar 2008
Phi(4,2^7658614+1)/2

23·7·163 Posts

Quote:
 Originally Posted by MisterBitcoin ECM pretest takes ~4 hours. The C122 took 50 minutes to complete, with 1 core. :)
Seconded - pretest should amount to ~10% of the cost of honest factoring or less.

Also, with a snfs polynomial this jobs will take a couple minutes, not 50! Are you factoring them as gnfs?

2018-11-07, 19:22   #8
MisterBitcoin

"Nuri, the dragon :P"
Jul 2016
Good old Germany

2·7·53 Posts

Quote:
 Originally Posted by Batalov Seconded - pretest should amount to ~10% of the cost of honest factoring or less. Also, with a snfs polynomial this jobs will take a couple minutes, not 50! Are you factoring them as gnfs?

As I said I was only using 1 thread.
The latest number (C123) took ~13 Minutes to finish using 6 threads. Log attached.

I´m using factmsieve.pl und the poly from factordb (These are not perfect, but they work ).
I used a pretest level of t38, looks like its a bit to much.
Attached Files
 test.log (19.1 KB, 111 views)

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