20090814, 05:40  #1 
May 2007
Kansas; USA
7^{2}·11·19 Posts 
Sieving drive Riesel base 6 n=150K1M
This is a sieving drive for the 8 k's remaining on Riesel base 6 for n=150K1M. Karsten kindly provided his file that is sieved to P=0.8T as a starting point.
Sieving up to P=43T is needed for the n=500K1M range for the 5 remaining k's. Like before, sr2sieve is what we will use. It is recommended that you run 64bit sr2sieve on a 64bit machine. Let us know if you need the executable or more detailed instructions on using it. Here is an example of the command to execute at the command prompt: sr2sieve p 35e12 P 40e12 i sieverieselbase6500K1M.txt The above would be if you were sieving P=35T40T. The file is listed after the "i" command and is the actual file name that is posted in a link below. Feel free to name it something shorter if you want or use the "srwork" older convention where you don't have to specify a file name. When complete, you should have a factors.txt file. Just post the file here in this thread or if it is too big, please Email the file to me at: gbarnes017 at gmail dot com A P=1T range should take ~2 CPU days on a modern 64bit machine. Please reserve ranges in multiples of P=1T and plan to reserve no more than ~710 days of work at a time. When making reservations, please post your estimated completion date. This can be seen in sr2sieve about one minute after you start your sieve. Here is a link to the latest sieve file: http://www.noprimeleftbehind.net/cru...e6500K1M.txt. All factors up to P=43T have been removed. We will remove additional factors as the drive progresses to slightly speed up sieving. Reservations: Code:
Prange reserved by status est. completion date 0T0.8T kar_bon complete 0.8T32T Lennart complete 32T35T gd_barnes complete 35T39T Flatlander complete 39T43T Batalov complete This is a very exciting base that can easily be proven within the next few years. All help is greatly appreciated! Thank you, Gary Last fiddled with by gd_barnes on 20100627 at 02:21 Reason: update status 
20090814, 09:41  #2 
May 2007
Kansas; USA
7^{2}·11·19 Posts 
Important note about the sieve file: Although it is included in the file, k=1597 was only sieved to n=500K. If anyone would like to take on the task of sieving just this one k for n=500K1M up to our current sieving limit for the drive, let me know and we'll keep a nonformal posting about what ranges are being done and who is doing them if more than one person.
Gary 
20090814, 11:17  #3  
"Lennart"
Jun 2007
2^{5}·5·7 Posts 
Quote:
I take k 1597 Lennart 

20090814, 15:58  #4 
"Lennart"
Jun 2007
2^{5}·5·7 Posts 
I have done k=1597 to 800G
I start sieve all from 800G3T Lennart 
20090814, 18:51  #5 
May 2007
Kansas; USA
7^{2}·11·19 Posts 
Thanks for the huge boost Lennart.

20090815, 20:17  #6 
"Lennart"
Jun 2007
460_{16} Posts 
Sieved to 6T
Here is the file sieved to 6T
Lennart 
20090818, 01:35  #7 
May 2007
Kansas; USA
7^{2}·11·19 Posts 
Thanks a bunch Lennart!
To all: In the next few hours, we'll start a drive for Riesel base 6 starting from n=150K on the final 8 k's remaining. With such a low base and few k's remaining, this one has a very good possibility of being proven over the next few years. As a SWAG without doing any math or calculation, I would put its final prime in the vicinity of n=~10M. Gary Last fiddled with by gd_barnes on 20090818 at 02:08 
20090818, 05:33  #8 
A Sunny Moo
Aug 2007
USA (GMT5)
79^{2} Posts 
YOWCH! Even with the new and improved PFGW, a test at that size for base 6 would probably take days to complete. Of course, that's not factoring in any expected increases in computer technology between now and when we get near that point.

20090818, 06:30  #9  
May 2007
Kansas; USA
7^{2}×11×19 Posts 
Quote:
I agree with your comments but believe me, that is very good for most of the bases here. I think there's a reasonable chance that we could prove it in 1020 years depending on how much we dedicate to it. That's for the Riesel side but on the Sierp side, with 28 k's remaining, it likely will not be proven in any of our lifetimes even allowing for computer speed increases and improvements in software unless new mathematical methods are discovered for searching the bases. Even if it was base 2, it would likely be more difficult than the Riesel side. People don't realize how hard it is to knock out the final k's on these bases. Even for a fairly prime base like base 6, it's tough because the final few k's are almost always very low weight. Consider that there are only 5128 pairs remaining for the entire n=150K1M range for k=1597 on a sieve to P=6T. k=1597 will be the key as it is by far the lowest weight k remaining. If we can pick up a prime for it for n<=1M, then there's a reasonable chance that we could find them all by n=3M to 5M. If not, well, this may end up being yet another base that we have one k remaining on for an extended period. All of that said, I still consider base 6 to be very exciting because it is the only truly "low" base that is kind of difficult to prove but not so overwhelmingly so that one side can't be done in our lifetimes. In this case, I define "low" as < 8. All other bases < 8 will be terribly difficult to prove in many lifetimes (Sierp base 2 has a chance but still a somewhat low chance at this point since it's already at n>10M with 5 k's remaining). I believe these "somewhat difficult" bases are the most interesting. An example is the Dual Sierp base 2 project with 3 k's remaining at n=~3M. I think that one has a good chance of being proven by perhaps the n=20M to 30M range. In other words, it's tough but not too tough, the most interesting kind. Gary Last fiddled with by gd_barnes on 20090818 at 06:42 

20090818, 14:43  #10  
A Sunny Moo
Aug 2007
USA (GMT5)
79^{2} Posts 
Quote:


20090929, 08:47  #11 
May 2007
Kansas; USA
7^{2}·11·19 Posts 
The Riesel base 6 drive is closing in on completion to n=500K. Therefore we will need additional sieving for the n=500K1M portion of the file. The optimum sieve depth for breaking off the n=500K750K range is P=50T. We (mostly Lennart) have already sieved up to P=32T.
A P=1T range should take ~2 CPU days and we are asking that people reserve ranges in at least P=1T increments. I am reserving P=32T35T for one core. ETA is Oct. 5th. Any and all help is greatly appreciated. Thank you, Gary Last fiddled with by gd_barnes on 20090929 at 09:12 
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