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Forum: Riesel Prime Search 2021-03-01, 09:52
Replies: 401
Views: 59,956
Posted By bur
What are (near-)Woodall k's? I know about...

What are (near-)Woodall k's? I know about near-Woodall primes where k is n-1, but that doesn't seem to be the case here.
Forum: Miscellaneous Math 2021-02-26, 08:55
Replies: 11
Views: 372
Posted By bur
Thanks for the links, sweety439. To be honest,...

Thanks for the links, sweety439. To be honest, understanding that Boklan and Conway paper is beyond me. So the conjecture says the number of primes is not only finite, but that there are only a few,...
Forum: mersenne.ca 2021-02-26, 07:01
Replies: 7
Views: 237
Posted By bur
Ok, thanks. I didn't mean that all prime...

Ok, thanks.

I didn't mean that all prime factors have to be shown in their full decimal representation regardless of size. Have a look at the site now (manual reload might be required), that's...
Forum: mersenne.ca 2021-02-25, 08:44
Replies: 7
Views: 237
Posted By bur
I think I now understand that the layout comes...

I think I now understand that the layout comes from factorizing the number and every time a factor is found it's added, until only one is left and that isn't show because work is done.

But why not...
Forum: mersenne.ca 2021-02-25, 08:06
Replies: 7
Views: 237
Posted By bur
List of factors on mersenne.ca

Take for example 2^1051-1 (https://www.mersenne.ca/exponent/1051). It's listed as fully factored, yet the website only shows 3 of these factors and says "Known prime factors (3 factors, 456.3 bits,...
Forum: Miscellaneous Math 2021-02-24, 18:38
Replies: 11
Views: 372
Posted By bur
I didn't know about this conjecture. That is also...

I didn't know about this conjecture. That is also why generalized Fermat numbers are supposed to only have a finite number of primes per base?


Does that conjecture have a name and is there a...
Forum: Miscellaneous Math 2021-02-24, 14:07
Replies: 11
Views: 372
Posted By bur
Mersenne-Woodall Primes

I saw that 2^{521} - 1 is a Mersenne prime and also the Woodall prime 512 * 2^{512} - 1.

A Mersenne number is a Woodall number if the exponent p is of the form 2^n + n. So obviously we need p to...
Forum: Proth Prime Search 2021-02-18, 06:57
Replies: 8
Views: 440
Posted By bur
I think the breaking-off-or-not depends on the...

I think the breaking-off-or-not depends on the time-scale. Splitting the range will speed up the sieving at the moment. However, in the long run overall sieving time would be shorter when sieving...
Forum: Homework Help 2021-02-16, 10:23
Replies: 8
Views: 469
Posted By bur
I guess I didn't make clear what my issue is. ...

I guess I didn't make clear what my issue is.

As I wrote, I am not looking for special treatment of Sierpinski or Mersenne. I am looking at a general question involving only the Prime Number...
Forum: Homework Help 2021-02-16, 09:03
Replies: 8
Views: 469
Posted By bur
Thanks, I read that article before and it seems...

Thanks, I read that article before and it seems to deal specifically with Mersenne primes.

I am more generally interested in the number of primes. I just chose the Mersenne form because it's so...
Forum: Homework Help 2021-02-16, 08:54
Replies: 8
Views: 469
Posted By bur
Number of primes 2^n-1 within certain range of n

I wanted to calculate how many primes of the form 2^n - 1 can be exptected within a certain range of n based purely on the prime number theorem x/ln(x), no special considerations such as n has to be...
Forum: Information & Answers 2021-02-14, 06:54
Replies: 11
Views: 847
Posted By bur
Batalov, do you refer to Primegrid? ...

Batalov, do you refer to Primegrid?


There's no real doublecheck anymore, but from what I read the new system provides the same level of safety.
Forum: Proth Prime Search 2021-02-13, 07:33
Replies: 8
Views: 440
Posted By bur
VBCurtis, yes, I'm using sr1sieve which was the...

VBCurtis, yes, I'm using sr1sieve which was the fastest among the various srsieves for this task. Good advice to feed candidates from the sieve to LLR testing. I guess I would remove all those...
Forum: Proth Prime Search 2021-02-12, 06:54
Replies: 8
Views: 440
Posted By bur
LaurV, thanks for the advice. I read here...

LaurV, thanks for the advice.

I read here and at PG that time per factor found increases only with sqrt(n), so I was explicitly told not to split the sieve. At the beginning I did just that...
Forum: Proth Prime Search 2021-02-11, 18:41
Replies: 8
Views: 440
Posted By bur
Proth primes with k = 1281979

Because I was interested how sieving worked and also wanted to test Proth20 (proth testing for GPU), I started looking at 1281979 * 2^n +1.

That k is large enough not to get into PG's various...
Forum: Riesel Prime Search 2021-01-26, 07:13
Replies: 238
Views: 38,173
Posted By bur
I only saw this now, sorry. Sounds convincing at...

I only saw this now, sorry. Sounds convincing at first, but why not use 2 out of 10 threads, or 7 or all?

Fundamentally you have two methods to remove a candidate for good, TF or PRP. If one is...
Forum: And now for something completely different 2021-01-21, 07:36
Replies: 3
Views: 546
Posted By bur
I checked other primes of this person and he/she...

I checked other primes of this person and he/she often uses primes or primorials as k. So I assumed it was about having k's with many or few small factors.

But you're right, maybe I'm giving it...
Forum: And now for something completely different 2021-01-20, 12:51
Replies: 3
Views: 546
Posted By bur
Correction: Should read "high weight". And...

Correction: Should read "high weight".

And now that I thought about it some more, k = 1153#-1 is a large k with few small factors but more elegant than using a 486 digit prime. Maybe that's the...
Forum: And now for something completely different 2021-01-20, 09:43
Replies: 3
Views: 546
Posted By bur
2^1571237 · (1153# - 1) + 1 - why was it constructed like that?

2^1571237 * (1153# - 1) + 1 is a new prime submitted to PrimePages (https://primes.utm.edu/primes/page.php?id=131592).

It is almost a PrimoProth...
Forum: Data 2021-01-12, 11:40
Replies: 5
Views: 5,165
Posted By bur
From the Primo FAQ...

From the Primo FAQ (http://www.ellipsa.eu/public/primo/primo.html#FAQ):
For serious prime search you might as well setup a Linux machine, but for just playing around it would be nice to have a...
Forum: Riesel Prime Search 2020-12-16, 09:08
Replies: 88
Views: 22,202
Posted By bur
I find it really inspiring how long you've been...

I find it really inspiring how long you've been working on this k. I started sieving for Proth k=1281979 some months back, now I'm at around 250T as well, but only for n < 4.1M. So 2 cores produce a...
Forum: Riesel Prime Search 2020-12-14, 07:05
Replies: 238
Views: 38,173
Posted By bur
If the same computer doing the sieving could...

If the same computer doing the sieving could eliminate candidates faster by using PRP, what's the advantage of sieving? Or vice versa.
Forum: And now for something completely different 2020-11-11, 18:18
Replies: 14
Views: 1,373
Posted By bur
Two questions... ;) Firstly: why choose...

Two questions... ;)


Firstly: why choose the form x + y * z# +1? It's specifically the x + ... I don't get. If you want to go for N-1, wouldn't that require a product + 1? So why not test x * z#...
Forum: And now for something completely different 2020-11-10, 18:15
Replies: 40
Views: 14,819
Posted By bur
Does anyone know if the lists are still actively...

Does anyone know if the lists are still actively maintained? And is the search organized in any way? PG has a generalized C/W project, but it only covers bases up to 140 or so. Where did the others...
Forum: Proth Prime Search 2020-10-18, 15:42
Replies: 27
Views: 12,019
Posted By bur
At PG forum it was said that sr1sieve is supposed...

At PG forum it was said that sr1sieve is supposed to be faster than sr2sieve for fixed k, so I wanted to give it a try, but cannot find binary for windows. Deoes someone have a link? Thanks.

...
Showing results 1 to 25 of 54

 
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