20151210, 19:53  #1 
Sep 2011
Germany
3,019 Posts 
Sieving for CRUS
Hi Followers,
If someone is able to sieve some S/R Bases from 25100k this would be great. Also 100200k and 200400k are welcome. I am out of running these ranges soon in BOINC and I don't want to lose time. Thx in advance! See recent posts in this thread for incomplete sieving reservations. See completed sieve files in the righthand column of our reservations pages here: http://www.noprimeleftbehind.net/cru...ereserves.htm http://www.noprimeleftbehind.net/cru...ereserves.htm Last fiddled with by gd_barnes on 20180127 at 12:21 Reason: general info and links 
20151210, 21:12  #2  
May 2007
Kansas; USA
10100100110011_{2} Posts 
Quote:
http://www.noprimeleftbehind.net/cru...sunproven.htm Most of them will be 100200k or 200k400k. There are a lot of bases in that area that can more easily be proven or reduced to 1k or 2k remaining by BOINC. 

20151211, 06:30  #3 
Romulan Interpreter
"name field"
Jun 2011
Thailand
2×4,903 Posts 
Ok, can you tell me one base I could sieve, preferable sr1sieve or sr2sieve job, the limits to go to (about) and the time frame when you need it, and I can allocate some resources to it.

20151211, 06:34  #4 
I moo ablest echo power!
May 2013
3·5·7·17 Posts 
I'm sieving R347 (with its remaining k of 22) from n=200k to 400k. Not quite to P=1e12 yet, at which point I'll run a PRP test to get a feel for how far I need to sieve.

20151211, 10:08  #5 
May 2007
Kansas; USA
53×199 Posts 
Using that list in the link that I posted above, the lowest difficulty bases are S428, S638, and S332. (Wombatman is doing R347.) I'd suggest starting with S428 for n=200k400k.

20151211, 10:32  #6 
Romulan Interpreter
"name field"
Jun 2011
Thailand
23116_{8} Posts 
Ok, sieving S428 for n>200k for a while, to see what's going on. Starting in one hour. Do you need factors file?

20151211, 10:56  #7 
May 2007
Kansas; USA
53×199 Posts 

20151211, 11:04  #8 
May 2009
Russia, Moscow
3·19·47 Posts 
I have sieve file for S333 100K250K, but sieve limit is only 1T. Will sieve deeply and send file to Gary.
Last fiddled with by gd_barnes on 20160103 at 10:15 Reason: R333 > S333 
20151211, 11:54  #9 
May 2008
Wilmington, DE
101100100100_{2} Posts 
Check for doubles
People should check when starting a sieve for a base and range to see if the other side (Riesel or Sierp) has the same base with the same range and sieve them together. Saves time and resources.
I'll be working on the 25K100K range doing the doubles first. We don't take sieving reservations so using this thread to give a general area of work would help out a bit. 
20151211, 14:21  #10 
Romulan Interpreter
"name field"
Jun 2011
Thailand
2×4,903 Posts 
R428 seems proven, which saves me of the troubles to learn how use srXsieve to sieve both sides in the same time...
Last fiddled with by LaurV on 20151211 at 14:22 
20151213, 04:31  #11 
Romulan Interpreter
"name field"
Jun 2011
Thailand
2·4,903 Posts 
S428 200k<n<1M sieved to 2e12 (it was faster than I expected). At this score, I have ~125 seconds per factor, which would mean ~1000 seconds per factor in the 200k300k range. Some cllr test in the same cpu says about 18002000 seconds for one test.
There are <7500 candidates remaining in 200k<n<1M. Question for the people knowing more about this subject: how much further should I go with sieving? And should I post the file here (~70kB) or send it to Gary?  In the same time I ran cllr in a different core for 8*428^n+1 for n to about 70k (continuing)  this is a doublecheck. Gary, do you need residue file for DC purposes?  I also ran lowsieving and cllr for all other k's (as there are only 9 all together) for n>=2, as I just didn't like those numbers being prime for n=1. This is for the category "futile work", but it still can be posted like a puzzle. I found primes for n higher than 1 for all of them, except 2 and 6, but 6 is eliminated by algebraic factorization, it seems that all of them are divisible by 7. So here the primes with higher n: Code:
2*428^1+1 = 857 is prime! (trial divisions) 5*428^1+1 = 2141 is prime! (trial divisions) 9*428^1+1 = 3853 is prime! (trial divisions) 3*428^2+1 = 549553 is prime! (trial divisions) 7*428^2+1 = 1282289 is prime! (trial divisions) 9*428^3+1 = 705624769 is prime! (trial divisions) 1*428^32+1 is prime! (85 decimal digits) Time : 9.273 ms. 3*428^15+1 is prime! (40 decimal digits) Time : 9.067 ms. 4*428^14+1 is prime! (38 decimal digits) Time : 13.575 ms. 5*428^21+1 is prime! (56 decimal digits) Time : 9.341 ms. 7*428^20+1 is prime! (54 decimal digits) Time : 9.544 ms. 9*428^1665+1 is prime! (4383 decimal digits) Time : 156.265 ms. (I am not so happy with the prime for k=4 also, as that is long known, and not a "new find", hehe, but I didn't do any action in that direction. ) One outcome from this futile playing with numbers is that I uncovered a small bug in cllr. My first sieving file was including 10*428^n+1 too, and it was sieving from n=0, therefore after srsieve kept 10*428^0+1 (which is prime) and eliminated all the other, so in the resulted sieved file (I stopped srsieve at 1e8 and continued with sr2sieve, then split and used sr1sieve for 2 and 8)  so in resulted file after first application of the srsieve, the 2*428^1+1 (=857, prime) followed after 10*428^0+1 (=11, also prime). In this very particular situation, cllr is testing the first one, and says it's prime, but is skipping the other one (i.e. misses the prime 857). Now I know this is a buggy situation, which will never happen in real life, but I wonder which other primes it can miss... Last fiddled with by LaurV on 20151213 at 04:35 
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