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Old 2010-05-25, 08:29   #1
Oddball
 
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May 2010

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Lightbulb Operation Megabit Twin

This is a side project that looks for twins and sophies of the form k*2^1000000+/- 1. It's a hybrid of the n=390000 effort and Primegrid's n=666666 Sophie Germain search. Basically, there are three stages of sieving: in the first stage, everything from k=1-120T was sieved up to p=100G with NewPGen's "LM" (lucky minus) option. This stage was finished in mid-July, and the contributors are shown below.

Code:
Range of k     User       
0T-1T          Oddball       
1T-3T          amphoria   
3T-4T          Oddball       
4T-7T          Flatlander   
7T-8T          amphoria    
8T-9T          Merfighters   
9T-10T         Flatlander    
10T-12T        amphoria     
12T-13T        Flatlander   
13T-14T        amphoria    
14T-16T        Flatlander    
16T-17T        Oddball        
17T-18T        amphoria    
18T-19T        Flatlander    
19T-20T        amphoria    
20T-21T        Lennart        
21T-22T        amphoria    
22T-23T        Oddball        
23T-29T        amphoria    
29T-32T        Oddball        
32T-34T        amphoria    
34T-65T        Flatlander    
65T-69T        amphoria    
69T-73T        Oddball       
73T-76T        Flatlander  
76T-79T        amphoria    
79T-83T        Flatlander    
83T-87T        amphoria    
87T-90T        Oddball       
90T-94T        Flatlander   
94T-98T        amphoria    
98T-100T       Oddball        
100T-104T      amphoria    
104T-106T      Oddball        
106T-109T      amphoria    
109T-111T      Oddball        
111T-114T      amphoria    
114T-118T      Flatlander    
118T-120T      Oddball
In the next stage, the range was sieved from p=100G to p=45T for twins only. It was broken down into 6 files that are 20T each. This stage was finished on September 18, 2010, and the contributors are shown below.

Code:
Range of k    User 
0-20T        amphoria     
20T-40T      amphoria     
40T-60T      amphoria      
60T-80T      Flatlander   
80T-100T     Flatlander    
100T-120T    amphoria
The 6 sieved files are combined into one file, which is sieved only for twins from p=45T to p=100P. If you're interested in participating, use NewPGen to sieve an available range below and upload the NewPGen.del file to sendspace when you're done. Currently, the status looks like this:

Code:
Range of p        User             Status
45T-60T          amphoria         complete
60T-61T          Dougal           complete
61T-62T          Oddball          complete
62T-70T          Dougal           complete
70T-80T          amphoria         complete
80T-100T         Dougal           complete
100T-140T        amphoria         complete
140T-240T        Dougal           complete
240T-350T        amphoria         complete
350T-500T        Dougal           complete
500T-550T        amphoria         complete
550T-750T        Dougal           complete
750T-800T        amphoria         complete
800T-801T        firejuggler      complete
801T-4000T       amphoria         complete
4000T-4800T      Puzzle-Peter     complete
4800T-5000T      monst            complete
5000T-5800T      amphoria         complete
5800T-6000T      amphoria         complete
6000T-6400T      amphoria         complete
6400T-6405T      firejuggler      complete
6405T-6600T      amphoria         complete
6600T-7600T      KEP              complete
7600T-10100T     amphoria         complete
10100T-12500T    amphoria         complete
12500T-14800T    amphoria         complete
14800T-17000T    amphoria         complete
17000T-17200T    Neo              complete
17200T-17443T    Neo              complete
17443T-18000T    amphoria         in progress
18000T-18200T    Neo              complete
18200T-18500T    amphoria         in progress
18500T-18735T    Neo              complete
18735T-19000T    amphoria         in progress
19000T-20000T    odicin           complete
20000T-20300T    odicin           complete
20300T-20400T    odicin           complete
20400T-20800T    odicin           in progress
20800T-21000T    odicin           complete
21000T-23200T    amphoria         complete
23200T-26200T    amphoria         complete
26200T-26600T    amphoria         in progress
26600T-27800T    amphoria         complete
27800T-29000T    amphoria         in progress
29000T+          available
Eventually, LLR testing will be opened, and Operation Megabit Twin will be declared a success if and when a n=1,000,000 twin is found.

You have three chances of getting a world record if a prime is found. For example, if 66555*2^1000000-1 is prime, 66555*2^1000000+1 will be checked for twins. Later, both 66555*2^999999-1 and 66555*2^1000001-1 will be checked for sophies. Even if neither of those three numbers are prime, your original prime will still be able to get into the top 5000 list.

Sieve file: http://www.amphoria.co.uk/megabit-twin/

Last fiddled with by Oddball on 2012-04-30 at 06:33 Reason: update
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Old 2010-05-25, 08:45   #2
Oddball
 
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Stats:
Code:
Rank     User               T sieved
1        amphoria             20991
2        odicin               1600
3        KEP                  1000
4        Neo                  878
5        Puzzle-Peter         800
6        Dougal               479
7        monst                200
8        Flatlander           94
9        Oddball              23
10       firejuggler          6
11       Merfighters          1
11       Lennart              1
The stats are calculated based on T sieved. If you sieved k=10T-11T in stage 1, you'll get one point. If you sieved k=20T-40T in stage 2, you get 20 points. If you sieved the file from p=45T-50T in stage 3, you get 5 points.

Last fiddled with by Oddball on 2012-04-30 at 06:34
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Old 2010-05-25, 21:01   #3
amphoria
 
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Taking k=1T-2T.
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Old 2010-05-27, 08:05   #4
Oddball
 
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File for k=1-205G, sieved to 24G:

http://www.sendspace.com/file/onovek

No, this isn't intended to be a list of numbers to be LLRed; it's just a save point for my progress. I'm running it on an old computer, so I'm a bit worried that the hard drive may crash.

Just throwing some numbers around:

Odds that a random candidate in this file will yield a twin: 1 in 266 million
Odds of hitting the Powerball jackpot if you buy one ticket: 1 in 195 million
Odds of hitting the Mega Millions jackpot if you buy one ticket: 1 in 176 million
Odds that a random candidate in this file will yield a sophie germain: 1 in 133 million
Odds that a random candidate in this file will yield either a twin or a sophie germain: 1 in 89 million

Odds of getting a straight flush if you're dealt five cards: 1 in 72200
Odds of having all tails or all heads if you flip a coin 15 times: 1 in 16400
Odds that a random candidate in this file will be prime: 1 in 16300
Odds of getting four of a kind if you're dealt five cards: 1 in 4200

Odds of getting snake eyes twice in a row if you roll two dice: 1 in 1300
Odds that one of the candidates in the file will yield a twin: 1 in 1000
Odds that one of the candidates in the file will yield a sophie germain: 1 in 500
Odds that one of the candidates in the file will yield either a twin or a sophie germain: 1 in 340

Estimated number of single primes in the file: 16
Number of miles in an average American's commute: 16

Last fiddled with by Oddball on 2010-05-27 at 08:06
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Old 2010-05-27, 10:52   #5
Merfighters
 
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Nice project!
I'm going to contribute to this project as soon as my computer finishes the current work.
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Old 2010-05-28, 16:03   #6
amphoria
 
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1T-2T complete to p=100G.

Taking 2T-3T.

http://www.sendspace.com/file/o90yun
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Old 2010-05-28, 21:47   #7
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should "verify results" be checked?
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Old 2010-05-29, 04:13   #8
Oddball
 
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Quote:
Originally Posted by agent1 View Post
should "verify results" be checked?
It's highly recommended for stage 1 (lucky minus sieve to p=100G) and required for stage 2 (twin sieve past 100G). But if you run the sieve on stable hardware and forget to check "verify results" for stage 1, you don't have to re-do the sieve.

Here's what the NewPGen contents file has to say about it:
Quote:
it is recommended that it is always checked, particularly as p gets large (where the scope for programming errors increases), and only uncheck it during the early parts of the sieving if you are using a primorial mode and many k's are being thrown out every second. If you are not using a primorial sieve then leave this checked, as then it makes no difference to NewPGen's performance.
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Old 2010-05-30, 11:26   #9
Flatlander
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Hi

Approx. how long would it take to sieve 1T on 1 core of a Q6700 @ 2.66GHz?

Chris
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Old 2010-05-30, 14:40   #10
amphoria
 
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Quote:
Originally Posted by Flatlander View Post
Hi

Approx. how long would it take to sieve 1T on 1 core of a Q6700 @ 2.66GHz?

Chris
I am sieving on a slower processor. But extrapolating from that I would guess about 2.5 days.
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Old 2010-05-30, 16:37   #11
Flatlander
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Okay, thanks.

Taking 4T-5T.
(I started a few hours ago but didn't want to commit myself. Didn't want to wake to find myself overlapping someone else's work by taking 3T-4T. )

Off topic edit:
(Hmmm. Time for me to find a new avatar.)

Last fiddled with by Flatlander on 2010-05-30 at 16:43
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