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Search: Posts Made By: R. Gerbicz
Forum: MattcAnderson 2021-10-18, 20:17
Replies: 24
Views: 503
Posted By R. Gerbicz
Still in high school's math camp we constructed a...

Still in high school's math camp we constructed a regular 17-gon.



There is an elementary way to show that if you can make a regular m and n-gon [using straightedge and compass] and gcd(m,n)=1...
Forum: Programming 2021-10-11, 16:47
Replies: 24
Views: 1,145
Posted By R. Gerbicz
That looks like good, maybe not the best example,...

That looks like good, maybe not the best example, there omega(n1)=omega(n2)=1, it was Sardonicus's tiny number.
As said S2 should be sorted.
Forum: Programming 2021-10-10, 20:05
Replies: 24
Views: 1,145
Posted By R. Gerbicz
It's nice that you've coded it. Try it for...

It's nice that you've coded it.
Try it for n=6402373705728000, that is 18!, it is missing a bunch of divisors, the first is 7, as I've looked all of these larger factorials are missing some...
Forum: Programming 2021-10-06, 19:55
Replies: 24
Views: 1,145
Posted By R. Gerbicz
Say d1=4 from S1 then the divisors that using...

Say d1=4 from S1 then the divisors that using this d1 is just:
1*d1
3*d1
9*d1
27*d1
for example we are at d=3*d1 and this was the smallest divisor, then the next smallest (using this d1) will be...
Forum: Programming 2021-10-04, 15:38
Replies: 24
Views: 1,145
Posted By R. Gerbicz
That is too much in memory, and running time if...

That is too much in memory, and running time if you request only (say) 4 batches of divisors.

There is a meet in the middle solution that is using (basically) only O(log(n)*(B+sqrt(D))) bits of...
Forum: y-cruncher 2021-08-17, 20:44
Replies: 68
Views: 50,012
Posted By R. Gerbicz
And what algorithm has been used? Chudnovsky, or...

And what algorithm has been used? Chudnovsky, or better: https://mersenneforum.org/showpost.php?p=558249&postcount=8 .
Forum: Computer Science & Computational Number Theory 2021-08-10, 11:43
Replies: 20
Views: 3,531
Posted By R. Gerbicz
Time in O(n*loglog(n)) is also possible, because...

Time in O(n*loglog(n)) is also possible, because with easy proof you can assume that you can always choose d=p prime, where p^2<=n.

When you compute the sequence:
W(n)<=min{W(n/p): p|n and...
Forum: Puzzles 2021-08-08, 14:20
Replies: 13
Views: 1,064
Posted By R. Gerbicz
Why, because you see somewhere in the problem the...

Why, because you see somewhere in the problem the 12 and 7 numbers?
Then solve this:

His boyhood lasted one sixth of his life, he married after one ninth more, his beard grew after one eighteenth...
Forum: GpuOwl 2021-07-26, 18:53
Replies: 4
Views: 622
Posted By R. Gerbicz
Quite pointless for a good implementation. But...

Quite pointless for a good implementation. But you have to be a little careful, because you can get also an FFT error in the error check [and also when you update the ladder prod(t=0,k,b**(2**(t*L)))...
Forum: Hardware 2021-07-21, 20:47
Replies: 221
Views: 35,530
Posted By R. Gerbicz
That is suboptimal. Start the tests with some...

That is suboptimal. Start the tests with some delay, so there will be at most one in the p-1 phase.
Starting exactly 4 is problematic: say 3 of them is in the prp test (with already done p-1 phase),...
Forum: Marin's Mersenne-aries 2021-07-03, 14:28
Replies: 23
Views: 1,344
Posted By R. Gerbicz
Yes, that could be true. But even gpuowl...

Yes, that could be true.

But even gpuowl could do the job faster: since you get the residue for p-1 only at the end for a fused p-1/prp run you can't do a middle p-1 run.Workaround: start two p-1...
Forum: Miscellaneous Math 2021-07-02, 13:14
Replies: 12
Views: 1,085
Posted By R. Gerbicz
Take: N-N^(1/8)<x<=N

Take: N-N^(1/8)<x<=N
Forum: Miscellaneous Math 2021-07-02, 13:02
Replies: 12
Views: 1,085
Posted By R. Gerbicz
Sometimes I like the easy problems (but we're...

Sometimes I like the easy problems (but we're different) :
any 0<=x<N^(1/8) do the job.
Forum: mersenne.ca 2021-07-01, 10:19
Replies: 24
Views: 2,227
Posted By R. Gerbicz
It is on the edge, but I think that all Mp is...

It is on the edge, but I think that all Mp is squarefree. My heuristic:

For fixed p prime, we need [q=2*k*p+1 prime] q^2 | Mp.
First we have 1/log(q) probability that q is prime.
We know that...
Forum: Factoring 2021-06-30, 19:42
Replies: 3
Views: 567
Posted By R. Gerbicz
No, you need also that x1 and x2 are integers(!),...

No, you need also that x1 and x2 are integers(!), and with this it is an integer optimization problem [without easy 'shortcuts"], you can try it out using say GLPK (it is free). And it is quite well...
Forum: Software 2021-06-28, 19:49
Replies: 479
Views: 51,793
Posted By R. Gerbicz
For example on M33391 we know a pretty large d...

For example on M33391 we know a pretty large d (=p1*p2*p3*p4) divisor which enables a good error checking at least on the first stage of P+-1 : do the computation also in Z[d] and then regularly do...
Forum: Prime Gap Searches 2021-06-21, 18:08
Replies: 63
Views: 7,356
Posted By R. Gerbicz
That is great! So we were really close to this (p...

That is great! So we were really close to this (p ~ 2^64+23e15) by our exhaustive search up to 2^64 with my code (+some code improvements from users here).
Forum: Number Theory Discussion Group 2021-06-10, 01:05
Replies: 10
Views: 2,024
Posted By R. Gerbicz
a+b*I=1 looks like good for every f.

a+b*I=1 looks like good for every f.
Forum: Puzzles 2021-06-06, 00:36
Replies: 20
Views: 3,427
Posted By R. Gerbicz
An offline version of the puzzle, where you need...

An offline version of the puzzle, where you need to give all of your guesses in advance,
so you can profit nothing from the previous answers.
For n=10 here it is a solution that is using "only" 23...
Forum: Conjectures 'R Us 2021-06-04, 01:02
Replies: 993
Views: 122,198
Posted By R. Gerbicz
We are expecting that basically all of these (say...

We are expecting that basically all of these (say >1000 digits) Prps are really primes, so not composite.
Forum: Conjectures 'R Us 2021-06-04, 00:50
Replies: 993
Views: 122,198
Posted By R. Gerbicz
Not very surprising.

Not very surprising.
Forum: Puzzles 2021-06-02, 22:49
Replies: 20
Views: 3,427
Posted By R. Gerbicz
You need at least (1-eps)*n guesses on average...

You need at least (1-eps)*n guesses on average (for fixed eps>0 and for that large n).
Proof:
On the k-th level (after k guesses) there are at most (n+1)^k nodes, because each answer could be only...
Forum: YAFU 2021-06-02, 21:12
Replies: 15
Views: 1,425
Posted By R. Gerbicz
A small bug, on line=76 we need: ...

A small bug, on line=76 we need:

while(mpz_sgn(S)!=0){

since in the next line we'll divide by S
[in most cases we won't reach S=0 so the full continued fraction expansion because we exit much...
Forum: YAFU 2021-06-02, 20:59
Replies: 15
Views: 1,425
Posted By R. Gerbicz
Yes, you can use/modify etc. the code.

Yes, you can use/modify etc. the code.
Forum: YAFU 2021-06-02, 02:07
Replies: 15
Views: 1,425
Posted By R. Gerbicz
OK, here it is a solution, thought that it is a...

OK, here it is a solution, thought that it is a much easier code.
In a few seconds:

gerbicz@gerbicz-MS-7972:~/gmp-6.1.2$ ./f...
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