20090414, 11:45  #1 
Feb 2007
211 Posts 
What if we don't find twin prime n=333333?
What is the probability that we will find twin prime for n=333333 before 100G is up?
What if we don't find a twin prime before 100G? do we start sieving 100G to 200G? or do we abandon n=333333 for a higher n=Value? Thanks 
20090414, 14:20  #2 
Aug 2008
Good old Germany
3×47 Posts 
Over at primegrid Lennart said, that they will stop LLR until the sieve is at 12P. I´ve seen for myself, that sieving needs atm ~45 seconds for one k and a LLRtest takes 2:40 minutes.
I think that nobody expected, that we will need so long to find this little twin. One of the problems ist, that primes you find here (no twin) will not get into the top5000. And so not many people are interested. But on the other hand, in the last few days were more than 2 times more LLRtest were crunched at Primegrid. And for myself I would like to see the end of this project. There must be a twin! ;) Hopefully it is not to far in the future... 
20090415, 15:28  #3  
Apprentice Crank
Mar 2006
2·227 Posts 
Quote:
There are no plans for sieving 100G200G, so it looks like we'll abandon n=333333 for a higher nvalue. 

20090415, 15:35  #4 
Aug 2008
Good old Germany
3×47 Posts 
Oh, doesn´t sound good. But we will see. I´m switching now back to sieving until at least sunday. should be the next n? n=666666?
Last fiddled with by Svenie25 on 20090415 at 15:43 
20090416, 02:48  #5 
Mar 2003
New Zealand
13×89 Posts 
It should be possible to make a program that sieves x different (carefully chosen) exponents at once at only a small extra cost in time (but requiring x times more memory).
Minimising the number of 1 bits in the binary expansion of the exponent should also reduce sieve time (i.e. an exponent which is a power of two would be fastest). E.g. sieving n=2^19+1=524289 and n=2^19+2^18+1=786433 together should be almost as fast as sieving n=524289 alone. 
20090416, 21:53  #6 
Sep 2004
13·41 Posts 
A 64 bit sieve would be good too. But it would be good to have a n that finds top5000 primes again.

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