mersenneforum.org 5*2^n-1 undersieved in Psieve files, n>3M
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 2012-09-14, 05:12 #1 shanecruise     Mar 2012 Hyderabad, India 3·17 Posts 5*2^n-1 undersieved in Psieve files, n>3M plus i tried sr1seive on one of the 3M range in 5*2^n-1 drive, and could remove 10 factors in 5 minutes shouldn't we consider updating them. Also is this sr1sieve great for mersenne prime? k=1
 2012-09-14, 09:34 #2 Kosmaj     Nov 2003 2×1,811 Posts Regarding 5*n^2-1, can you tell us which file have you tried to sieve, and what factors have you found? Those test files are not the latest version, but they are fairly new, from a sieving file released a few months ago. Last fiddled with by Kosmaj on 2012-09-14 at 12:34
 2012-09-14, 10:02 #3 shanecruise     Mar 2012 Hyderabad, India 3·17 Posts @kosmaj here is an example [shashank@iota sr1sieve-1.4.1-bin]$./sr1sieve-x86_64-linux -i 3170to3172.txt -o 3170-72new.txt -P 10000000000 sr1sieve 1.4.1 -- A sieve for one sequence k*b^n+/-1. Read 96 terms for 5*2^n-1 from NewPGen file 3170to3172.txt'. sr1sieve 1.4.1 started: 3170014 <= n <= 3171990, 1000000000 <= p <= 10000000000 1043838949 | 5*2^3170044-1 1560478571 | 5*2^3170682-1 2041977359 | 5*2^3170070-1 4315418641 | 5*2^3171180-1 8725797991 | 5*2^3170714-1 8788835771 | 5*2^3171554-1 p=8788953629, 45064789 p/sec, 6 factors, 86.5% done, 28 sec/factor sr1sieve 1.4.1 stopped: at p=10000000000 because range is complete. Wrote 90 terms for 5*2^n-1 to NewPGen file 3170-72new.txt'. Note "28sec/factor" I could sieve more _________________________ more sr1sieve 1.4.1 started: 3170014 <= n <= 3171990, 10000000000 <= p <= 30000000000 11785244819 | 5*2^3171588-1 15222573571 | 5*2^3171614-1 16227917989 | 5*2^3171194-1 21866270731 | 5*2^3170634-1 22354234291 | 5*2^3170344-1 28403730361 | 5*2^3171214-1 29964540439 | 5*2^3170980-1 p=29964625319, 45712439 p/sec, 7 factors, 99.8% done, ETA 14 Sep 15:40 Last fiddled with by shanecruise on 2012-09-14 at 10:11 2012-09-14, 10:55 #4 Thomas11 Feb 2003 1,901 Posts Quote:  Originally Posted by shanecruise @kosmaj here is an example [shashank@iota sr1sieve-1.4.1-bin]$ ./sr1sieve-x86_64-linux -i 3170to3172.txt -o 3170-72new.txt -P 10000000000 sr1sieve 1.4.1 -- A sieve for one sequence k*b^n+/-1. Read 96 terms for 5*2^n-1 from NewPGen file 3170to3172.txt'. sr1sieve 1.4.1 started: 3170014 <= n <= 3171990, 1000000000 <= p <= 10000000000 1043838949 | 5*2^3170044-1 1560478571 | 5*2^3170682-1 2041977359 | 5*2^3170070-1 ...
That's indeed interesting. Thanks for pointing this out, Shanecruise!

Verification with Pari shows that these are indeed proper factors.
So, most probably those factors were somehow lost in the initial stage of the sieve file preparation.
Is anyone in contact with the PrimeSearch team?

 2012-09-14, 11:00 #5 shanecruise     Mar 2012 Hyderabad, India 3316 Posts seive files are only till 1 Billion , we can easily do 100 Billion in less than 30 minutes. I have only extended it. same goes for 8th drive. I guess we need to seive deeper and there's no need to give credit to pSeive anymore, its outdated
 2012-09-14, 11:13 #6 Thomas11     Feb 2003 1,901 Posts I just putted all k<300 into one file and ran sr2sieve on it. It seems that only k=5 is affected: Code: ./sr2sieve -i sr_2.abcd -p 1000000000 -P 2000000000 sr2sieve 1.8.9 -- A sieve for multiple sequences k*b^n+/-1 or b^n+/-k. Read 4180903 terms for 148 sequences from ABCD format file sr_2.abcd'. Split 148 base 2 sequences into 3117 base 2^60 subsequences. Expecting to find factors for about 135315.90 terms in this range. sr2sieve 1.8.9 started: 3000000 <= n <= 4000000, 1000000000 <= p <= 2000000000 1000682041 | 5*2^3740864-1 1000968181 | 5*2^3237128-1 1000982629 | 5*2^3139532-1 1001250689 | 5*2^3529918-1 1002273931 | 5*2^3277698-1 1002291839 | 5*2^3453994-1 1002751229 | 5*2^3602168-1 1002788879 | 5*2^3580938-1 1003213439 | 5*2^3700772-1 ... The missing factors are starting from p=1,000,000,000. I haven't found any below this. Last fiddled with by Thomas11 on 2012-09-14 at 11:14
2012-09-14, 11:17   #7
Thomas11

Feb 2003

190110 Posts

Quote:
 Originally Posted by shanecruise seive files are only till 1 Billion , we can easily do 100 Billion in less than 30 minutes. I have only extended it. same goes for 8th drive.
Those indicators, e.g. "1000000000:M:1:2:258", are just placeholders. This wasn't updated by the PrimeSearch team.

The 8th drive shouldn't be affected. At least I hope so...

Last fiddled with by Thomas11 on 2012-09-14 at 11:18

 2012-09-14, 11:17 #8 shanecruise     Mar 2012 Hyderabad, India 638 Posts ok yes you are right only k=5 is affected. others look ok so we can update that one.
2012-09-14, 12:09   #9
Kosmaj

Nov 2003

1110001001102 Posts

Hi guys,
can you try to sieve the enclosed file, it's the latest Psieve version of July 27.

Thanks!
Attached Files
 k5_3M.txt.gz (109.1 KB, 40 views)

2012-09-14, 12:23   #10
Kosmaj

Nov 2003

E2616 Posts

Sorry, no need to sieve, it's exactly the same file like the one on the server with all those composites.

How about k=7, I tried a little but found no factors from 1-4E9. Thanks!
Attached Files
 k7_3M.txt.gz (39.3 KB, 39 views)

2012-09-14, 13:12   #11
Thomas11

Feb 2003

1,901 Posts

Quote:
 Originally Posted by Kosmaj Sorry, no need to sieve, it's exactly the same file like the one on the server with all those composites. How about k=7, I tried a little but found no factors from 1-4E9. Thanks!
I tried all k<300 and only k=5 seems to be affected. See my earlier posting.
Seems that the composites/factors file starting from p=1B was lost.

Meanwhile I tested the n=4-5M sieve file and there are also missing factors:
Code:
./sr1sieve -i t17_b2_k5.npg -o test.txt -p 1000000000 -P 2000000000
sr1sieve 1.4.1 -- A sieve for one sequence k*b^n+/-1.
Read 42582 terms for 5*2^n-1 from NewPGen file t17_b2_k5.npg'.
sr1sieve 1.4.1 started: 4000004 <= n <= 4999954, 1000000000 <= p <= 2000000000
1000077409 | 5*2^4085350-1
1000636969 | 5*2^4123310-1
1000706821 | 5*2^4056718-1
1000721539 | 5*2^4950400-1
1000920451 | 5*2^4037194-1
1001099629 | 5*2^4141240-1`
Thus, I suggest that we put k=5 on hold until we've investigated this a little further.
I will put the whole n=3-6M range for k=5 into one file and start sieving from p=1B.
Perhaps someone else could start at higher levels and try to locate the upper bound of the missing factors file. Maybe only p=1B-1T is lost...

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