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Old 2007-09-02, 11:39   #12
kar_bon
 
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hello gary,
i found another page maintained by Dale Andrews with primes for k=301 to 999.
some of your missing primes are in that list, most of yours not. last updates of these pages were in 2006. perhaps another list to crosscheck with our pages! i think most of the primes from PrimeSearch.
here the link: http://www.geocities.com/Primes_R_Us/riesel/index.html
karsten
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Old 2007-09-02, 17:51   #13
gd_barnes
 
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Quote:
Originally Posted by kar_bon View Post
hello gary,
i found another page maintained by Dale Andrews with primes for k=301 to 999.
some of your missing primes are in that list, most of yours not. last updates of these pages were in 2006. perhaps another list to crosscheck with our pages! i think most of the primes from PrimeSearch.
karsten

Excellent! I have a free day today to do nothing much at all. (I don't really have a life!) I'll check it all vs. our site.


Gary
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Old 2007-09-03, 03:19   #14
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Default Corrections 300<k<1000 RPS vs. Geocities

I have checked all of the Geocities primes in the range of 300 < k < 1000. In addition to what I have already posted in this thread, I found the following additional problems on RPS that were copied over from Prime Search:

Missing primes:
789*2^61569-1
789*2^62484-1
789*2^66164-1
945*2^31062-1

Incorrect primes:
495*2^50883-1 should be 495*2^50833-1
609*2^57709-1 should be 609*2^57769-1
635*2^132162-1 should be 635*2^132548-1
873*2^44250-1 should be 873*2^44251-1
959*2^26248-1 should be 959*2^26428-1


All of the above were LLR'd. The missing and corrected k-n combos checked out as prime and the incorrect ones checked out as composite.

Geocities had found 4 of the 15 missing primes primes that I had previously listed as differences in this thread here, had correctly listed the 3 incorrect primes that I previously listed here, and correctly did not have the one composite k-n combo that I listed here. But they were still missing 11 of the 15 prior missing primes plus MANY primes on their site for n > 75K that we had, many from my effort to sync up the top-5000 site with our primes.

There were no differences found with Geocities that I should have already caught with my effort so far. All of the above are either n > 50K or ( k > 750 and n > 25K). It looks like all of what I found except one correction would have been caught anyway when I extend the effort up to n = 75K. But I'm confident that there will be more than just the above when I do!


Gary

Last fiddled with by gd_barnes on 2007-09-03 at 03:31
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Old 2007-09-07, 20:42   #15
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Default Remaining problems for k=300-1001 to n=50K & other

The LLR for n=25K to 50K has now completed the range of 300 < k <=1001. I found the following additional problems that have not already been shown in this thread:

Missing primes:
827*2^38822-1
855*2^37925-1
939*2^49307-1
951*2^29539-1

All were LLR'd a second time and were confirmed prime. Also all missing and incorrect primes on the comparison with Geocities for this range of n were confirmed.

For the range of 300 < k <= 1001 and 25K <= n < 50K, this makes a total of 11 missing and 3 incorrect primes that were copied over from prime search. Here is the updated error rate for k=300-1001:

n=0 to 10K; 1 error out of 7066 primes = 0.01%
n=10K to 25K; 9 out of 940 = 0.96%
n=25K to 50K; 14 out of 716 = 1.96% <=== :surprised

(To put a ~2% error rate in perspective, if all ranges of n had that high of an error rate and the avg. k has 50 primes, it would be an avg. of one error for every k!)

For completeness and a triple-check, here is the status for k < 300 up to n=50K:
Sieve complete up to n=50K for all k's.
LLR complete up to n=25K for all k's.
LLR complete for n=25K to 50K for k <= 85.
k <= 85 verified from n=10K to 50K.
85 < k < 250 verified from n=10K to 25K.
250 < k < 300 verified from n=0 to 25K.
No problems found so far.
LLR is currently working on 85 < k < 300 for n=25K to 50K.

Kosmaj, for the 6 k's that you wanted me to check, LLR has now completed up to n=210K. Since the last status report, no problems have been found and two more primes were confirmed.

Confirmed primes:
257 194312
217 205525

Upcoming double check work is mostly the same as the last status report with some added effort on #3. #1 is about 10 days or so from completion, #2 should be done in 3-4 days, and for #3, I have identified many more k's for 300 < k <= 1001 that have unusually large gaps between their primes. Those will be added to the effort.


Gary
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Old 2007-09-12, 23:56   #16
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Default A most unusual error...

I was doing a twin prime search a couple of days ago on all of the Riesel's on our site for k < 1000 by searching them for Proth's. Imagine my surprise when 825*2^129236+1 came out as prime, meaning that I had myself a top-10 twin the easy way! Double-checking confirmed it. But imagine my irritation when it turns out that 825*2^129236-1 is NOT prime!

Correction:
Remove the prime 825*2^129236-1 from our site. It has a factor of 233. Not surprisingly, someone had mismarked a Proth prime as a Riesel prime on Prime Search.


Gary
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Old 2007-09-16, 23:33   #17
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Default Verification complete k<=1001 to n=50K and other

I have now completed the double-check effort for all k <= 1001 up to n=50K. This effectively includes a triple-check for k < 300 for that range. No additional missing or incorrect primes have been found. This completes #'s 2 and 5 from my original double-check work list.

Kosmaj, #1 on my original work list, the effort to double check the 6 k's that you wanted, was up to n=245K as of Friday afternoon. Additional primes shown below have been confirmed. No missing or incorrect primes have been found so far.

Confirmed primes:
215 224036
203 235480


Upcoming double-check work:

1. Complete double-check requested by Kosmaj for k=109, 203, 205, 215, 217, and 257. With all k's except for low-weight k=109 dropping out at n=250K or 260K, I expect completion in about 2-3 days.

2. Test and check primes found by others on 2 of my k's for ranges previously shown in this thread. After doing a quick preliminary test, I decided not to put my slow borrowed machine on this. Even though it's a much smaller effort than #1, it would STILL take too long! I will start on it in approx. 1-2 months after finishing #1 -and- completing sieving k=5 to P=20T -and- completing sieving on k=243 for ranges and to levels yet to be determined.

3. Test and check multiple k's already identified that have unusually large prime gaps for 300 < k <= 1001 up to n=100K. Later on, extend the range to n=150K and then possibly 200K depending on the size of the prime gaps on the individual k's. (After #1 and #2.)

4. I would ultimately like to double-check 300 < k <= 1001 up to n=100K but that will probably be sometime in 2008, perhaps around the time I extend 1001 < k < 10K up to n=25K after my heavy-weight tests up to n=400K are complete. Either one of those efforts would probably need at least 3 cores to complete in a reasonable amount of time.


This was a GOOD status report!


Gary

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Old 2007-09-17, 01:57   #18
mdettweiler
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Quote:
Originally Posted by gd_barnes View Post
I have now completed the double-check effort for all k <= 1001 up to n=50K. This effectively includes a triple-check for k < 300 for that range. No additional missing or incorrect primes have been found. This completes #'s 2 and 5 from my original double-check work list.

Kosmaj, #1 on my original work list, the effort to double check the 6 k's that you wanted, was up to n=245K as of Friday afternoon. Additional primes shown below have been confirmed. No missing or incorrect primes have been found so far.

Confirmed primes:
215 224036
203 235480


Upcoming double-check work:

1. Complete double-check requested by Kosmaj for k=109, 203, 205, 215, 217, and 257. With all k's except for low-weight k=109 dropping out at n=250K or 260K, I expect completion in about 2-3 days.

2. Test and check primes found by others on 2 of my k's for ranges previously shown in this thread. After doing a quick preliminary test, I decided not to put my slow borrowed machine on this. Even though it's a much smaller effort than #1, it would STILL take too long! I will start on it in approx. 1-2 months after finishing #1 -and- completing sieving k=5 to P=20T -and- completing sieving on k=243 for ranges and to levels yet to be determined.

3. Test and check multiple k's already identified that have unusually large prime gaps for 300 < k <= 1001 up to n=100K. Later on, extend the range to n=150K and then possibly 200K depending on the size of the prime gaps on the individual k's. (After #1 and #2.)

4. I would ultimately like to double-check 300 < k <= 1001 up to n=100K but that will probably be sometime in 2008, perhaps around the time I extend 1001 < k < 10K up to n=25K after my heavy-weight tests up to n=400K are complete. Either one of those efforts would probably need at least 3 cores to complete in a reasonable amount of time.


This was a GOOD status report!


Gary
Why don't you start a distributed doublecheck effort? I'm sure it would speed things up drastically.
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Old 2007-09-17, 02:40   #19
gd_barnes
 
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Default Distributed double-checking; what a concept! :-)

Quote:
Originally Posted by Anonymous View Post
Why don't you start a distributed doublecheck effort? I'm sure it would speed things up drastically.
I'd be glad to! The only problem is, not too many people are fond of double-checking. Also, like Kosmaj says and I agree, over-clocked machines cannot be used for double-checking, which eliminates more people. (none of mine are)

If I sieved a range of 300 < k <= 1001 from n=50K to 100K, would you be willing to LLR some of it? I can guarantee there will be some errors found and I know for me, I need to find an error or two to make it 'feel' like it is worth it!

The only problem is, my main machines that I use for this effort are tied up with sieving on k=5 right now and after 9/25, on another important k that I want to take care of. Like I mentioned, it'll be about 1-2 months before I can free one up. I could just move my #4 up on the priority list to #2 as shown in my last post if I had some people to help with it.


Gary
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Old 2007-09-17, 03:43   #20
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Gary

I'd like to thank you for double checking the 6 k's I mentioned.

As far as k<300 and n<100,000 are concerned, they have already been double checked on a professional, error-free hardware, and some k/ranges have been checked 3 or more times. You are clearly wasting you time there.
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Old 2007-09-17, 04:10   #21
mdettweiler
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Quote:
Originally Posted by gd_barnes View Post
I'd be glad to! The only problem is, not too many people are fond of double-checking. Also, like Kosmaj says and I agree, over-clocked machines cannot be used for double-checking, which eliminates more people. (none of mine are)

If I sieved a range of 300 < k <= 1001 from n=50K to 100K, would you be willing to LLR some of it? I can guarantee there will be some errors found and I know for me, I need to find an error or two to make it 'feel' like it is worth it!

The only problem is, my main machines that I use for this effort are tied up with sieving on k=5 right now and after 9/25, on another important k that I want to take care of. Like I mentioned, it'll be about 1-2 months before I can free one up. I could just move my #4 up on the priority list to #2 as shown in my last post if I had some people to help with it.
Alas, my resources are very small (essentially consisting of one P4 3.2Ghz HT). However, given that the ranges to test are small enough, I might be able to do some LLR doublecheck testing for you. How big would the ranges be? I would prefer if they could be small enough so that they don't take more than a week apiece to test. My computer is on for, I would guess, an average of 8-9 hours a day--and I know from working on the k=105 search here that n's around 650,000 take about an hour apiece to test , so if based on those calculations you could come up with a range that would take approximately a week for me to process, then I might be able to do some.

If you'd like to get some more resources for doublechecking than my drop-in-the-bucket resources, then you could start a reservation thread here for doublechecking--making it clear at the beginning of the thread that this is only for non-overclocked systems and that in mostly, there won't be much of the glory of finding new primes--and I'm sure you'll attract a bunch of users who don't care as much about finding primes to be attached to their name and care more about what's in the best interests of the project. It worked over at Riesel Sieve--for a while they ran a separate LLRNet server for doublechecking, and from what I can tell there were a bunch of people with decently large resources crunching for it. (The doublechecking LLRNet server has now been replaced with an LLR component to their BOINC setup [although the BOINC part of the project is diverted from doublechecking work to assault a particular stubborn k at the moment].)

P.S.: You could always set up an LLRNet server for doublechecking. Since none of the first-pass projects here have an LLRNet server set up, you might be able to get some users that way who would rather a set-it-and-forget-it solution for, say, large farms that are too much work to maintain manually. Of course, overclockers would have to be left out, but I'm sure that there's plenty of users who don't overclock and would be glad to do doublechecking work simply because LLRNet could take care of it automatically for them.

Last fiddled with by mdettweiler on 2007-09-17 at 04:13
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Old 2007-09-18, 04:21   #22
gd_barnes
 
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Default Web page for reporting status...

Kosmaj and Karsten,

See my post in the 'post small primes and tell us about your progress' thread about the web page that I have created for reporting statuses. Status of double-checking will also be on the page.


Gary

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