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 2016-04-17, 17:53 #12 lalera     Jul 2003 2×307 Posts hi, I do like to reserve base=6 n=1 to 50000 for double checking
 2016-04-17, 21:07 #13 lalera     Jul 2003 2·307 Posts hi, cksieve v1.1.0 gives out a warning - what does it means? Code: cksieve -P20e10 -i ck.in cksieve 1.1.0 -- A sieve for Carol (b^n-1)^2-2 and Kynea (b^n+1)^2-2 numbers. Read 16432 terms for (74^n+/-c)^2-2 from ABC file ck.in'. cksieve 1.1.0 started: 3 <= n <= 99999, 60000000000 <= p <= 200000000000 p=77153080019, 141204 p/sec, 150 factors, 12.3% done, 0 sec/factor, ETA 18 Apr 08:19 WARNING: 393216 is not a root (mod 77309411329) p=81621680057, 141347 p/sec, 190 factors, 15.4% done, 0 sec/factor, ETA 18 Apr 08:19
2016-04-18, 01:15   #14
rogue

"Mark"
Apr 2003
Between here and the

3·31·71 Posts

Quote:
 Originally Posted by lalera hi, cksieve v1.1.0 gives out a warning - what does it means? Code: cksieve -P20e10 -i ck.in cksieve 1.1.0 -- A sieve for Carol (b^n-1)^2-2 and Kynea (b^n+1)^2-2 numbers. Read 16432 terms for (74^n+/-c)^2-2 from ABC file ck.in'. cksieve 1.1.0 started: 3 <= n <= 99999, 60000000000 <= p <= 200000000000 p=77153080019, 141204 p/sec, 150 factors, 12.3% done, 0 sec/factor, ETA 18 Apr 08:19 WARNING: 393216 is not a root (mod 77309411329) p=81621680057, 141347 p/sec, 190 factors, 15.4% done, 0 sec/factor, ETA 18 Apr 08:19
There is a piece of code that finds x such at x^2 = 2 (mod p). Sometimes (and I mean rarely) it returns x where x^2 = -2 (mod p). I haven't looked into. Chances are well under 1 in a million that a factor is missed because of this.

 2016-04-18, 03:03 #15 axn     Jun 2003 2×2,683 Posts Incidentally, that output also show another bug. The factor removal rate is always "0 sec/factor".
 2016-04-18, 06:19 #16 Batalov     "Serge" Mar 2008 Phi(4,2^7658614+1)/2 3·29·113 Posts ...and the ETA seems way off. Or it may be in the wrong timezone (but not UTC, as one could immediately expect).
2016-04-18, 06:31   #17
axn

Jun 2003

2×2,683 Posts

Quote:
 Originally Posted by Batalov ...and the ETA seems way off. Or it may be in the wrong timezone (but not UTC, as one could immediately expect).
ETA is fine. It is in local timezone. It is the p/sec that is quirky. I believe it is counting actual p's being processed, rather than the p-range being processed (i.e. if it crunched from p=1e9 to p=2e9, it counts it as pi(2e9)-pi(1e9) p's processed rather than a range of 1e9 processed).

2016-04-18, 17:13   #18
rogue

"Mark"
Apr 2003
Between here and the

147138 Posts

Quote:
 Originally Posted by axn Incidentally, that output also show another bug. The factor removal rate is always "0 sec/factor".
I noticed that too. It shouldn't be too hard to fix.

2016-04-18, 17:17   #19
rogue

"Mark"
Apr 2003
Between here and the

3×31×71 Posts

Quote:
 Originally Posted by axn ETA is fine. It is in local timezone. It is the p/sec that is quirky. I believe it is counting actual p's being processed, rather than the p-range being processed (i.e. if it crunched from p=1e9 to p=2e9, it counts it as pi(2e9)-pi(1e9) p's processed rather than a range of 1e9 processed).
Correct. I treat "p/sec" as the number of primes tested per second not the size of the range sieved per second. If I were to use the latter, I wouldn't call it "p/sec" as that is misleading (IMO). ETA and removal rate should be all that one cares about.

 2016-04-18, 23:47 #20 rogue     "Mark" Apr 2003 Between here and the 3×31×71 Posts In the first post I updated to fix the factor removal rate.
2016-04-20, 11:33   #21
Batalov

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

3·29·113 Posts

Quote:
 Originally Posted by axn All proven primes, and available in factordb (the larger ones apparently cannot be proven in factordb, even though N+1 is adequately factored).
I noticed a kludge to get numbers > 30,000 digits (ostensibly, the default limit) proven:

Step 1. We can submit e.g. (40^40778+1)^2-2 -- as (40^40778+2)*40^40778-1
Step 2. Submit for PRP test. Because it has a ...-1 form, N+1 test is also run (or at least I thin this is how it happens).

Then we can query for (40^40778+1)^2-2 and because this is a shorter form it sticks. And it shows as a P.

2016-04-20, 11:47   #22
axn

Jun 2003

2×2,683 Posts

Quote:
 Originally Posted by Batalov I noticed a kludge to get numbers > 30,000 digits (ostensibly, the default limit) proven: Step 1. We can submit e.g. (40^40778+1)^2-2 -- as (40^40778+2)*40^40778-1 Step 2. Submit for PRP test. Because it has a ...-1 form, N+1 test is also run (or at least I thin this is how it happens). Then we can query for (40^40778+1)^2-2 and because this is a shorter form it sticks. And it shows as a P.
This is good to know. Nothing can be done about the ones already reported, but I will use this trick for any future finds.

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