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Old 2007-04-13, 05:05   #100
kar_bon
 
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Default 100th prime

475977645*2^240964-1 is prime.
This is the 100th prime for this k.
Close to fill the gap: n=0-242k and 250k-371,
overall 101 primes for now
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Old 2007-04-13, 12:25   #101
ValerieVonck
 
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Default k=16260063105

Primes for k= 16260063105 to n = 50000 for following n's:

Code:
6, 10, 16, 20, 28, 35, 43, 55, 57, 80, 86, 95, 110, 113, 117, 137,
150, 181, 199, 212, 224, 267, 280, 293, 307, 308, 348, 416, 511, 556,
557, 624, 637, 677, 785, 821, 876, 948, 1016, 1038, 1072, 1083, 1194,
1442, 1607, 1629, 1803, 1829, 1877, 1901, 1909, 2081, 2098, 2110,
2239, 2310, 2356, 2919, 2931, 2932, 3339, 3621, 4228, 4389, 5322,
6516, 6958, 7350, 7593, 7617, 7715, 7759, 8391, 8583, 9382, 10348,
11692, 12758, 15116, 21519, 22245, 23650, 26941, 28708, 30088, 35398,
39065, 39704, 40485, 44365, 46273, 47644, 49647

Last fiddled with by Kosmaj on 2007-07-10 at 05:43
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Old 2007-05-04, 01:10   #102
roger
 
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How far should I test to (n=) before accepting/rejecting a k value to continue it or not? At present my limit is 50 primes at n=10000 or less [if less than 50 primes before 10001, I don't continue.]
I'm seeing a lot primes per 'good' k value on this forum, but of course, everyone else has a better computer .

Thanks,

Roger
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Old 2007-05-04, 17:14   #103
lsoule
 
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In my past K searches, I would first look at the # of primes in n=0-5k.
If that yielded over 60 primes, I'd then look at 5-10k. Then, if it's still
producing, look at 10-50k. Over on the "Choose your own k thread", the
top Ks there have 90-102 primes in n=0-50k.

If you like really big Ks, check out the "A new very prime k" thread.
142 primes up to n=90k!
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Old 2007-05-04, 21:31   #104
roger
 
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Thanks Isoule,

That will help save a lot of time!

I'm interested in the ones that produce many primes, and from my small searches (to n=10000) the best ones have been primordials and multiple powers (eg 2^3*3^4).

Has this been explained?

Roger
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Old 2007-05-09, 20:03   #105
gd_barnes
 
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Default Primes for k=15015 to n=100K

15015 is a good consistent k with medium weight. I like it because it is a repeating '15' with a '0' in the middle and it is the product of the first 5 non-even primes, 3x5x7x11x13.

I've sieved and tested it to n=100K and will probably go to n=500K with it. For a medium-weight k, it's one of the more consistent ones I've seen so far. It has primes in every range of 10K, i.e. n=10 to 20K, n=20 to 30K, etc., even though there are only 61 primes to n=100K.

Here is the list so far:
1, 7, 15, 17, 18, 23, 34, 42, 49, 69, 131, 149, 154, 240, 260, 269, 275, 300, 303, 309, 351, 402, 413, 429, 471, 556, 916, 939, 1007, 1092, 1418, 1717, 2122, 2228, 2381, 2441, 2623, 2736, 4557, 4732, 6391, 7840, 9813, 9851, 10403, 10764, 18410, 24097, 32648, 38629, 41935, 43779, 44837, 47477, 50853, 56160, 65043, 73677, 80887, 94375, 94588


Gary

Last fiddled with by Kosmaj on 2007-07-27 at 23:49 Reason: n's moved in-line
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Old 2007-05-09, 22:46   #106
Kosmaj
 
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Note that it's already tested, most likely to 360k, by L94, Abraham, the largest found prime is 15015*2^356533-1.

Check the Top-5000 web site, the status page, and try Primes--> Search, use "%" as a wildcard for the exponent.

Many primorial Ks like this one (product of first n primes) have been already tested.
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Old 2007-05-10, 18:48   #107
gd_barnes
 
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Default 15015 already tested; now dropping my search

Ouch. Well, well...The newbie (me) gets burned. I searched this entire site as well as the 15K site and could find no mention of k=15015 or that it had been reserved. I now see the top 5,000 list has several K-15015 entries so I'll have to add that to my list of sites to check before embarking on a K search. Oh well, I was on the right track anyway. Of course I will drop my search.

Can the 15K site be updated for K=15015? Even though the site is now defunct, I thought we were attempting to keep it up to date.

Also, is there a place where I can find all of the K's that have been tested or are being tested and how far they've been tested? I find a smattering in various places here on the forum but no real comprehensive list. And all I could see on another site were for K's < 600. It seems difficult to get my hands on testing for K's > 600.

I'd like to find a relatively low (less than 1 million) K with medium to heavy weight that has not been worked. The higher K's clearly take much longer for the LLR program to compute.


Thanks,
Gary
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Old 2007-05-10, 20:28   #108
lsoule
 
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You should check out the thread "New data page" here - I think that
might be the most up-to-date that you can find. That and the top-5000
are the must-check places.

The basic problem is that we don't "own" any of the Ks. There are other
people who are searching riesel primes but do not coordinate with us.
It would be great if everyone did so that we didn't duplicate work, but...

For K's under 1M, I'm currently running a search to estimate the weight
of each K and can post it here when it's done (maybe later today).
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Old 2007-05-12, 16:42   #109
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Gary,
Although k=15015 has been already tested, the tested range is not very high. At the time, 3-4 years ago, n=360k with such a high-weight k was a considerable achievement, but nowadays with modern, fast cpu's it's considered a small exponent. Also, if you want your primes to survive for more than a month on Top-5000 you have to aim above n=333,333. Therefore, testing from the last known prime of 15015 is still a good idea, I think. You can sieve from 356 to 600 or 700k, and with a single but fast cpu reach 500k soon, and hopefully find a few primes on the way. But of course, there is no guarantee that primes are there. Compare with our k=210885 and a large, primeless gap between 315 and 550k.
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Old 2007-05-13, 10:45   #110
gd_barnes
 
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Default Primes for k=102765 to 100K; continuing testing

I've tested k=102765 to 100K. I plan to continue to 300-400K. I found the following 82 primes:

102765 1
102765 5
102765 7
102765 10
102765 18
102765 20
102765 21
102765 23
102765 26
102765 35
102765 39
102765 40
102765 41
102765 46
102765 48
102765 51
102765 57
102765 63
102765 69
102765 83
102765 87
102765 97
102765 105
102765 106
102765 120
102765 123
102765 144
102765 156
102765 208
102765 225
102765 303
102765 461
102765 579
102765 580
102765 656
102765 743
102765 758
102765 791
102765 815
102765 861
102765 886
102765 910
102765 926
102765 955
102765 1126
102765 1140
102765 1415
102765 1696
102765 2113
102765 2280
102765 2753
102765 2910
102765 3538
102765 3796
102765 4068
102765 4150
102765 4211
102765 4514
102765 6280
102765 6921
102765 7723
102765 9116
102765 9374
102765 11518
102765 12348
102765 12798
102765 14816
102765 18635
102765 18894
102765 21249
102765 21279
102765 22687
102765 29528
102765 35825
102765 38608
102765 39353
102765 40978
102765 50070
102765 66175
102765 68980
102765 85560
102765 91937


Gary
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