20070805, 04:04  #23 
Nov 2003
2·1,811 Posts 
It is really a pretty grouping, but GFs are very heavy weight, therefore I don't think it's unusual.
As for the speed, Proth.exe was specifically optimized for GF's. Maybe LLR is faster only for small k's. But Proth.exe has a limit on base b (in b^2^k+1), for k=16 I think it's about 2M (so only b<2M can be tested). As for the status of GF search, I think all values have been already extensively sieved and all them have been reserved but some people never completed their reserved ranges. Furthermore, about 2 years ago Yves Gallot who crated Proth.exe disappeared from the prime searching community, and since about that time GF projects began to lose popularity. BTW, the account is not anonymous, it's written in the disclaimer that they were found by Dirk Schlueter who doesn't have an account on Top5000. Most likely prof Caldwell found out about them through his private channels. Last fiddled with by Kosmaj on 20070806 at 01:33 
20070806, 04:15  #24 
Nov 2003
2·1,811 Posts 
I just realized that Dirk's bases are at the 17M level, which means he didn't use Proth.exe, but most likely genefer80, another software written by Yves Gallot which can work with a base of any size. But it's much slower than Proth.exe because it is simulating 80bit floating point precision in software. New 64bit cpu's support 80bit fp arithmetic nativelly but as I said Yves is not around to do the changes.

20070809, 20:24  #25 
Mar 2006
Germany
B52_{16} Posts 
new biggest Woodall prime
251749*2^20139951 is the new No.1 Woodall Prime (606279 digits)!

20070814, 21:37  #26 
May 2005
658_{16} Posts 

20070815, 04:58  #27 
Nov 2004
California
2^{3}·3·71 Posts 
With a k without a 3 or a 5 in it

20070815, 12:35  #28 
I quite division it
"Chris"
Feb 2005
England
81D_{16} Posts 
From his website:
"Currently we are focusing on fixed n candidates, which are faster than fixed k searches" 
20070903, 07:55  #29 
May 2005
2^{3}×7×29 Posts 
Looks like another record Woodall prime for Primegrid

20070903, 10:06  #30 
Nov 2003
2·1,811 Posts 
Yes, amazing, the previous one also at the 2M level was found less than a month ago...

20071101, 02:22  #31 
Nov 2003
2·1,811 Posts 
SOB striked again, with a huge prime
33661*2^7031232+1 with more than 2.1 M digits The 10th largest of all times. It's a result of their doublechecking effort and thus smaller than their previous prime (at n=13M). 
20071101, 15:42  #32  
May 2007
Kansas; USA
5·31·67 Posts 
Quote:
Way to go seventeenorbust!! That makes a good case for doublechecking I'd say! 

20071107, 12:38  #33 
Nov 2003
7046_{8} Posts 
3 Large GRUs
Congrats to Andy Steward on 3 new generalized repunits in top10! The largest one:
(13096^59531)/13095, 24506 digits is currently second largest, about 1500 digits more than the GRU found by Larry and me 2 years ago (the world record at the time), which is now 3rd. For each of his proven GRUs Andy provides a detailed commentary, so that with little selfstudy everybody can try to enter the field and find his first GRU. The commentary for the above prime can be found here. However, beware that entering Top20 is not easy! Kosmaj Last fiddled with by Kosmaj on 20071107 at 12:41 
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