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-   -   Reserved for MF - Sequence 3366 (https://www.mersenneforum.org/showthread.php?t=18449)

RichD 2013-08-08 23:30

Reserved for MF - Sequence 3366
 
Welcome,

Aliquot Sequence 3366 has been officially assigned to the forum ("Mersenne Forum") on 7 August, 2013.

It currently stands at index 2067 with 2^3 * 3^3 * ... * c135.

The status of ECM work on the c135 is unknown.

This thread will be the place holder for ECM progress and possibly initiation of some NFS processing. Team sieving will most likely be spun off into a separate thread until it completes. Then progress will return here for status updates.

Feel free to contribute curves or other electronic cycles you may want to donate.
And by all means - have fun!!

mod edit:
[url]http://www.factordb.com/sequences.php?se=1&aq=3366&action=last20&fr=0&to=100[/url]

RichD 2013-08-09 01:55

3366:i2067
 
After running a few hundred curves @ 43e6 I feel confident the c135 is ready for GNFS. (Not that those few curves make it happen but including the history of this Seq.) I've started it on a Core i5. It should finish in 4-5 days. I won't feel hurt if someone trumps me with an ECM find. :smile:

RichD 2013-08-10 15:49

c143 @ i2068
 
-pm1 2e9 - nothing
800 @ 1e6 - nothing

Passing through
400 @ 3e6

RichD 2013-08-11 05:05

2000 @ 3e6 - nothing.

EdH 2013-08-11 17:46

I'm well past 4000@11e6...

VBCurtis 2013-08-11 18:31

Poly select commencing. I should have one Monday morning USA-Pacific time.
-Curtis

EdH 2013-08-11 18:36

At 4745 curves @ 11e6, I switched to 43e6 for a while...

EdH 2013-08-12 03:52

At about 1660 curves @ 43000000:
[code]
$ python ecm.py -threads 2 -c 2000 43000000 <ecmIn
-> ___________________________________________________________________
-> | Running ecm.py, a Python driver for distributing GMP-ECM work |
-> | on a single machine. It is Copyright, 2012, David Cleaver and |
-> | is a conversion of factmsieve.py that is Copyright, 2010, Brian |
-> | Gladman. Version 0.10 (Python 2.6 or later) 30th Sep 2012. |
-> |_________________________________________________________________|

-> Number(s) to factor:
-> 82572604842970740226575313011024210867650562043391903215525706141475272605260959388176023149958914785033958356770086632201183899666330968322243 (143 digits)
->=============================================================================
-> Working on number: 825726048429707402...899666330968322243 (143 digits)
-> Currently working on: job5530.txt
-> Starting 2 instances of GMP-ECM...
-> ./ecm -c 1000 43000000 < job5530.txt > job5530_t00.txt
-> ./ecm -c 1000 43000000 < job5530.txt > job5530_t01.txt

GMP-ECM 6.4.4 [configured with GMP 5.1.2, --enable-asm-redc] [ECM]
Using B1=43000000, B2=240490660426, polynomial Dickson(12), 2 threads
Done 219/2000; avg s/curve: stg1 199.7s, stg2 57.81s; runtime: 28620s

Run 219 out of 2000:
Using B1=43000000, B2=240490660426, polynomial Dickson(12), sigma=2507321602
Step 1 took 200036ms
Step 2 took 57956ms
********** Factor found in step 2: 1207628288954874358756230750720893104793451481159
Found probable prime factor of 49 digits: 1207628288954874358756230750720893104793451481159
Probable prime cofactor 68375845115745085102927692017310006270434002895546517987965895954910700224363999707612562247077 has 95 digits
[/code]:smile:

RichD 2013-08-12 06:26

c121 @ i2069
 
-pm1 1e9 - nothing

This might be a personal run to finish off the c121.
Go for it EdH.

Clueless at 2^3 * 3^2 ... c121

EdH 2013-08-12 21:03

OK,
[code]
$ python ecm.py -threads 2 -c 2000 43000000 <ecmIn
...
-> Working on number: 859816614827472478...578490215531107749 (121 digits)
-> Currently working on: job4791.txt
-> Starting 2 instances of GMP-ECM...
-> ./ecm -c 1000 43000000 < job4791.txt > job4791_t00.txt
-> ./ecm -c 1000 43000000 < job4791.txt > job4791_t01.txt

GMP-ECM 6.4.4 [configured with GMP 5.1.1, --enable-asm-redc] [ECM]
Using B1=43000000, B2=240490660426, polynomial Dickson(12), 2 threads
Done 285/2000; avg s/curve: stg1 100.8s, stg2 36.44s; runtime: 19837s

Run 285 out of 2000:
Using B1=43000000, B2=240490660426, polynomial Dickson(12), sigma=306416374
Step 1 took 101114ms
Step 2 took 36583ms
********** Factor found in step 2: 154499827420010610820657248119651788418298611
Found probable prime factor of 45 digits: 154499827420010610820657248119651788418298611
Probable prime cofactor 55651622994376897358779815364928346078694944874963398571536226939862492842759 has 77 digits
[/code]:smile:

VBCurtis 2013-08-12 23:15

Note that 2000 curves at 43M here would take longer than GNFS by quite a margin, without certainty of producing a factor. In general, ECM for more than 25% of expected NFS factoring time is effort better spent on NFS. The ecm target of 30 to 33% of the digit length of the GNFS candidate came from this heuristic.

In this case, it worked nicely and saved you time! While B1 = 3e6 is the "right" choice for a t40, I find that using 11e6 costs little extra time for the t40 level, while increasing my chances of a factor the size you found (p45) pretty substantially. Even doing 250 43e6 curves is a t40, though a B1 that big would cost a fair amount more time for a t40 than a smaller choice. In fact, I've been meaning to sample a bunch of B1s to see which choice minimizes the time to complete a t45- I've done a few experiments before, and 11e6 is not optimal on my machines with gmp-ecm 6.4.

Edit: or was this just for fun?


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