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 [I]b[/I] (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 Top-5000. Most likely prof Caldwell found out about them through his private channels.

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 80-bit floating point precision in software. New 64-bit cpu's support 80-bit fp arithmetic nativelly but as I said Yves is not around to do the changes.

new biggest Woodall prime
 

251749*2^2013995-1 is the new No.1 Woodall Prime (606279 digits)!

[URL="http://primes.utm.edu/primes/page.php?id=81935"]Looks like "15k" is back[/URL].

With a k without a 3 or a 5 in it :grin:

From his website:
"Currently we are focusing on fixed n candidates, which are faster than fixed k searches"

Looks like [URL="http://primes.utm.edu/primes/page.php?id=82110"]another record Woodall[/URL] prime for Primegrid :tu:

Yes, amazing, the previous one also at the 2M level was found less than a month ago...

SOB striked again, with a huge prime

33661*2^7031232+1

with more than 2.1 M digits :shock: The 10th largest of all times. It's a result of their double-checking effort and thus smaller than their previous prime (at n=13M).

[quote=Kosmaj;117507]SOB striked again, with a huge prime

33661*2^7031232+1

with more than 2.1 M digits :shock: The 10th largest of all times. It's a result of their double-checking effort and thus smaller than their previous prime (at n=13M).[/quote]


Way to go seventeen-or-bust!! That makes a good case for double-checking I'd say! :smile:

3 Large GRUs
 

Congrats to Andy Steward on 3 new generalized rep-units in top-10! The largest one:
(13096^5953-1)/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 self-study everybody can try to enter the field and find his first GRU. The commentary for the above prime can be found [URL="http://www.primes.viner-steward.org/andy/E/33281741.html"]here[/URL].

However, beware that entering Top-20 is not easy!

Kosmaj