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Forum: And now for something completely different 2020-11-11, 18:18
Replies: 13
Views: 535
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: 33
Views: 10,651
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: 5,709
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.

...
Forum: Math 2020-10-14, 17:20
Replies: 12
Views: 696
Posted By bur
Having looked at the proof, what I don't get is,...

Having looked at the proof, what I don't get is, why is 2^{(2r+1)s}=(2^s + 1)(...)?

Wolfram expressed it differently as (2^a)^b = (2^a + 1)(2^{a(b-1)}-2^{a(b-2)}+...). For that proof, I don't...
Forum: Math 2020-10-14, 13:02
Replies: 12
Views: 696
Posted By bur
Ok, thanks. So 2^n+1 is proven to only be prime...

Ok, thanks. So 2^n+1 is proven to only be prime if it is a Fermat number.
Forum: Math 2020-10-14, 12:14
Replies: 12
Views: 696
Posted By bur
Not really related to this specific question, but...

Not really related to this specific question, but also a question about 2^n + 1:


Why aren't they researched in regard to being prime? It is basically a Proth number with k = 1. I just checked...
Forum: Software 2020-10-03, 06:01
Replies: 9
Views: 856
Posted By bur
Sorry, but I still don't get it. Using 2^n + 1...

Sorry, but I still don't get it. Using 2^n + 1 for the first 10 values we get:



3 5 9 17 33 65 129 257 513 1025


5 divides the 2nd, 6th and 10th candidate. So it divides not at most every...
Forum: Software 2020-09-29, 17:10
Replies: 9
Views: 856
Posted By bur
For the record, common sieving software DOES...

For the record, common sieving software DOES check all candidates in the sieve against a prime factor. The reason why you almost never see a prime dividing more than one candidate is simply that the...
Forum: Software 2020-09-14, 08:13
Replies: 9
Views: 856
Posted By bur
The thing is, what does happen is that a single...

The thing is, what does happen is that a single candidate is factored by more than one prime in a relatively small range.

The sieve file contains 65000 candidates and I was sieving in four...
Forum: Software 2020-09-13, 16:32
Replies: 9
Views: 856
Posted By bur
I don't really get it. The candidates aren't a...

I don't really get it. The candidates aren't a million consecutive numbers. Only the n is consecutive.

Say my primes are of magnitude 1E12 and candidates are k * 2^1E6 + 1. Then any of the primes...
Forum: Software 2020-09-12, 05:47
Replies: 9
Views: 856
Posted By bur
General question about sieving software

I'm not sure if this is the proper section, but anyway.

Sieve of Eratosthenes takes a prime, marks all multiples of it, then moves to the next unmarked number and so on. But when I view the output...
Forum: Riesel Prime Search 2020-09-09, 20:46
Replies: 383
Views: 44,416
Posted By bur
Here are the n values for Riesel primes with k =...

Here are the n values for Riesel primes with k = 1281979 and n <= 100000


3
7
43
79
107
157
269
Forum: Riesel Prime Search 2020-09-09, 09:54
Replies: 383
Views: 44,416
Posted By bur
Haha, I just realized this is probably trivial...

Haha, I just realized this is probably trivial and occurs for every divisor... yes, I'm not that good at math. :)
Forum: Riesel Prime Search 2020-09-09, 07:21
Replies: 383
Views: 44,416
Posted By bur
I looked into the matter why only primes show up...

I looked into the matter why only primes show up as n for low n values. Here are some restrictions I found:

If n \equiv 0 \textrm{ mod } 2 the Riesel number will be divisible by 3 (n = 2, 4, 6, 8,...
Forum: Riesel Prime Search 2020-09-08, 20:02
Replies: 383
Views: 44,416
Posted By bur
But then I would say low weight doesn't really...

But then I would say low weight doesn't really matter. Either I test 100000 candidates for a given k and find 10 primes or I test 10000 and find one. Then move to the next low weight k and in the end...
Forum: Riesel Prime Search 2020-09-08, 16:59
Replies: 383
Views: 44,416
Posted By bur
So the number of primes per n decreases stronger...

So the number of primes per n decreases stronger than the number of candidates per n?


Here are the n values that produce Riesel primes:

1281979 * 2^n - 1
0 <= n <= 20000

3
7
Forum: Riesel Prime Search 2020-09-08, 07:44
Replies: 383
Views: 44,416
Posted By bur
kar_bon, I never really understood the Nash...

kar_bon, I never really understood the Nash weight. It is an indicator for how many candidates remain after sieving? So I would think a low weight is good, since few candidates after sieving is...
Forum: Riesel Prime Search 2020-09-08, 05:39
Replies: 383
Views: 44,416
Posted By bur
I was testing k = 1281979 for n<= 100000 and...

I was testing k = 1281979 for n<= 100000 and interestingly the first 10 n for which this is prime are prime themselves. After that unfortunately there's n = 1005 which obviously isn't. But the ratio...
Forum: Software 2020-09-07, 17:22
Replies: 281
Views: 36,462
Posted By bur
I know this is an older post, but a screen saver...

I know this is an older post, but a screen saver isn't required anymore. In the past it really did save the screen because on the old CRTs the constant bombardment by electrons could alter the screen...
Forum: Proth Prime Search 2020-09-06, 17:44
Replies: 27
Views: 5,709
Posted By bur
I will do a comparison later, first I want to...

I will do a comparison later, first I want to finish sieving... I'm at 5e12 now and factors are coming in considerably slower, but still at about 3 min per factor. The range 3320000 <= n <= 4100000...
Forum: Software 2020-09-06, 17:26
Replies: 10
Views: 2,901
Posted By bur
Does anyone have win (32 or 64) binaries for it?

Does anyone have win (32 or 64) binaries for it?
Forum: Proth Prime Search 2020-09-04, 07:12
Replies: 27
Views: 5,709
Posted By bur
Thanks a lot for all the help so far! I read...

Thanks a lot for all the help so far!

I read about srsieve2, but wasn't sure if it's ready yet. Maybe rogue can say if for fixed k and n in the 3M-4M range which of sr1sieve, sr2sieve or srsieve2...
Forum: Proth Prime Search 2020-09-03, 17:11
Replies: 27
Views: 5,709
Posted By bur
I realized it's apparently not like that... (My...

I realized it's apparently not like that... (My intention was to utilize all four physical cores since the -t option doesn't work under Windows. Won't it speed up overall progress (not progress on...
Forum: Proth Prime Search 2020-09-02, 09:26
Replies: 27
Views: 5,709
Posted By bur
VBCurtis, you're right, makes sense not to change...

VBCurtis, you're right, makes sense not to change the abcd file when it's the input file. But after sieving, when I convert the sr2sieve output with srfile, then it would be helpful if that...
Forum: Proth Prime Search 2020-09-01, 19:36
Replies: 27
Views: 5,709
Posted By bur
Ok, manually updating the abcd file is what I do...

Ok, manually updating the abcd file is what I do now. I thought is was a neat feature of srsieve to include this info in the abcd file, why doesn't sr2sieve?


The -t option isn't accepted. I just...
Showing results 1 to 25 of 32

 
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