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 2007-04-13, 05:05 #100 kar_bon     Mar 2006 Germany 2·1,423 Posts 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
 2007-04-13, 12:25 #101 ValerieVonck     Mar 2004 Belgium 33×31 Posts 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
 2007-05-04, 01:10 #102 roger     Oct 2006 22·5·13 Posts 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
 2007-05-04, 17:14 #103 lsoule     Nov 2004 California 23·3·71 Posts 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!
 2007-05-04, 21:31 #104 roger     Oct 2006 4048 Posts 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
 2007-05-09, 20:03 #105 gd_barnes     May 2007 Kansas; USA 237358 Posts 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
 2007-05-09, 22:46 #106 Kosmaj     Nov 2003 1110001001102 Posts 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.
 2007-05-10, 18:48 #107 gd_barnes     May 2007 Kansas; USA 5×13×157 Posts 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
 2007-05-10, 20:28 #108 lsoule     Nov 2004 California 23×3×71 Posts 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).
 2007-05-12, 16:42 #109 Kosmaj     Nov 2003 1110001001102 Posts 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.
 2007-05-13, 10:45 #110 gd_barnes     May 2007 Kansas; USA 5·13·157 Posts 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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