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 2007-12-31, 08:33 #78 VBCurtis     "Curtis" Feb 2005 Riverside, CA 117216 Posts Riesel base 28: 8469*28^5421-1 is prime. -Curtis
 2007-12-31, 08:50 #79 VBCurtis     "Curtis" Feb 2005 Riverside, CA 2×7×11×29 Posts Riesel 28: 8469 yielded a prime in less than 20 min of work (5421, shown on primes thread). Reserving 6207 and 7367, to 25k. -Curtis Last fiddled with by VBCurtis on 2007-12-31 at 08:57
 2007-12-31, 21:36 #80 tnerual     Oct 2006 1000000112 Posts sierpinski base 28 1797*28^5681+1 is a probable prime. Time: 14.513 sec.
 2008-01-01, 03:35 #81 tnerual     Oct 2006 7·37 Posts 38562*16^26408+1 is prime! Time : 163.0 sec. first prime of the 2008 year !
 2008-01-01, 11:17 #82 VBCurtis     "Curtis" Feb 2005 Riverside, CA 105628 Posts 7367*28^23099-1 is prime.
 2008-01-01, 17:35 #83 tnerual     Oct 2006 7·37 Posts 2203*28^13911+1 is a probable prime. Time: 102.559 sec. by the way, all k*28^n+1 are tested up to n=13911 i will reserve the 6 last k for sierpinski base 28 (i will test them 'til i'm bored ) (i'm still testing my other reservations on base 16)
 2008-01-01, 21:24 #84 gd_barnes     May 2007 Kansas; USA 3×3,413 Posts Good finds Curtis and tnerual. Tnerual, I'll just reserve all of the remaining Sierp base 28 k's up to n=25K for you. If you stop before that or go higher, let me know. Tnerual, can you go ahead and prove the 'probable primes'? They need to be proven and not just a 'probable prime'. The program PFGW can prove them but LLR can not. LLR can only prove bases that are powers of 2 such as your base 16. The software for PFGW is available for download in the software thread. There are also instructions in the thread there and that come with the program. The interface is easy to use. If you've never used it, here is the command line that you would give it to prove one of your Sierp base 28 primes: pfgw -q1797*28^5681+1 -f0 -t The -t command is to prove "+1" primes. A -tp command would be used to prove "-1" primes. The -f0 command tells it to not do any small trial factoring (since it obviously has no small factors). You can also use the Proth program to prove them. It takes much longer to run but you may find it a little easier to understand. Because it takes longer, Proth is not included in the software thread. Any questions...feel free to send me a PM or post them right here. Thanks, Gary
 2008-01-01, 22:02 #85 tnerual     Oct 2006 7·37 Posts done : Code: PFGW Version 1.2.0 for Windows [FFT v23.8] Primality testing 1797*28^5681+1 [N-1, Brillhart-Lehmer-Selfridge] Running N-1 test using base 5 1797*28^5681+1 is prime! (17.3788s+0.0025s) Done. PFGW Version 1.2.0 for Windows [FFT v23.8] Primality testing 2203*28^13911+1 [N-1, Brillhart-Lehmer-Selfridge] Running N-1 test using base 3 2203*28^13911+1 is prime! (97.8790s+0.0016s) Done.
 2008-01-02, 00:58 #86 tnerual     Oct 2006 7×37 Posts i'm sorry to flood the topic but i have a new prime ... 59890*16^29827+1 is prime! Time : 187.0 sec. all k*16^n+1 tested up to n=30000 (except the 2 that belongs to other people) i release all sierpinski base 16 k except k=34543 (tested up to 41220) and k=35320 (tested up to 74269) (in short, my reservations are now 2 sierpinski base 16 and 6 sierpinski base 28)
2008-01-02, 01:12   #87
mdettweiler
A Sunny Moo

Aug 2007
USA (GMT-5)

624110 Posts

Sierpinski Base 16 k=2908 tested up to n=100k, no primes. I'm releasing this k. lresults is attached to this post. (Please note that the lresults is for the entire 25K-100K range, and it includes k=4885 up until a little bit after where I'd previously found a prime on there. Thus, part of my lresults file has already been posted here, but I figured I'd post the whole thing rather than just what hadn't been previously posted.)

I've started work on the Riesel Base 13 k=288 that I'd reserved. I'm surprised that it's taking as long as it is, though; is that just because it's not a power of 2? I know that LLR tests are quicker than PRP tests, but I didn't think they were that much quicker; however, I'm finding that tests that took about 600 seconds for Sierp. Base 16 for the same n-level are taking upwards of 1000 seconds for Riesel Base 13!
Attached Files
 lresults-base16Sierp.txt (189.9 KB, 147 views)

 2008-01-02, 08:23 #88 VBCurtis     "Curtis" Feb 2005 Riverside, CA 2·7·11·29 Posts Riesel 28: 7367 yielded a prime, noted in primes thread. 6207 complete to 25k, no prime. Starting 5886 tonight, with the rest of the 5000's to follow. All to 25k. Finding two primes so easily has me fueled to aim for all of Riesel 28 to 25k, but I'll reserve it in chunks in case I get distracted by another new search. -Curtis

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