20100525, 08:29  #1 
May 2010
763_{8} Posts 
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=1120T was sieved up to p=100G with NewPGen's "LM" (lucky minus) option. This stage was finished in midJuly, and the contributors are shown below.
Code:
Range of k User 0T1T Oddball 1T3T amphoria 3T4T Oddball 4T7T Flatlander 7T8T amphoria 8T9T Merfighters 9T10T Flatlander 10T12T amphoria 12T13T Flatlander 13T14T amphoria 14T16T Flatlander 16T17T Oddball 17T18T amphoria 18T19T Flatlander 19T20T amphoria 20T21T Lennart 21T22T amphoria 22T23T Oddball 23T29T amphoria 29T32T Oddball 32T34T amphoria 34T65T Flatlander 65T69T amphoria 69T73T Oddball 73T76T Flatlander 76T79T amphoria 79T83T Flatlander 83T87T amphoria 87T90T Oddball 90T94T Flatlander 94T98T amphoria 98T100T Oddball 100T104T amphoria 104T106T Oddball 106T109T amphoria 109T111T Oddball 111T114T amphoria 114T118T Flatlander 118T120T Oddball Code:
Range of k User 020T amphoria 20T40T amphoria 40T60T amphoria 60T80T Flatlander 80T100T Flatlander 100T120T amphoria Code:
Range of p User Status 45T60T amphoria complete 60T61T Dougal complete 61T62T Oddball complete 62T70T Dougal complete 70T80T amphoria complete 80T100T Dougal complete 100T140T amphoria complete 140T240T Dougal complete 240T350T amphoria complete 350T500T Dougal complete 500T550T amphoria complete 550T750T Dougal complete 750T800T amphoria complete 800T801T firejuggler complete 801T4000T amphoria complete 4000T4800T PuzzlePeter complete 4800T5000T monst complete 5000T5800T amphoria complete 5800T6000T amphoria complete 6000T6400T amphoria complete 6400T6405T firejuggler complete 6405T6600T amphoria complete 6600T7600T KEP complete 7600T10100T amphoria complete 10100T12500T amphoria complete 12500T14800T amphoria complete 14800T17000T amphoria complete 17000T17200T Neo complete 17200T17443T Neo complete 17443T18000T amphoria in progress 18000T18200T Neo complete 18200T18500T amphoria in progress 18500T18735T Neo complete 18735T19000T amphoria in progress 19000T20000T odicin complete 20000T20300T odicin complete 20300T20400T odicin complete 20400T20800T odicin in progress 20800T21000T odicin complete 21000T23200T amphoria complete 23200T26200T amphoria complete 26200T26600T amphoria in progress 26600T27800T amphoria complete 27800T29000T amphoria in progress 29000T+ available You have three chances of getting a world record if a prime is found. For example, if 66555*2^10000001 is prime, 66555*2^1000000+1 will be checked for twins. Later, both 66555*2^9999991 and 66555*2^10000011 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/megabittwin/ Last fiddled with by Oddball on 20120430 at 06:33 Reason: update 
20100525, 08:45  #2 
May 2010
763_{8} Posts 
Stats:
Code:
Rank User T sieved 1 amphoria 20991 2 odicin 1600 3 KEP 1000 4 Neo 878 5 PuzzlePeter 800 6 Dougal 479 7 monst 200 8 Flatlander 94 9 Oddball 23 10 firejuggler 6 11 Merfighters 1 11 Lennart 1 Last fiddled with by Oddball on 20120430 at 06:34 
20100525, 21:01  #3 
"Dave"
Sep 2005
UK
2·19·73 Posts 
Taking k=1T2T.

20100527, 08:05  #4 
May 2010
499 Posts 
File for k=1205G, 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 20100527 at 08:06 
20100527, 10:52  #5 
Mar 2010
On front of my laptop
1110111_{2} Posts 
Nice project!
I'm going to contribute to this project as soon as my computer finishes the current work. 
20100528, 16:03  #6 
"Dave"
Sep 2005
UK
2×19×73 Posts 

20100528, 21:47  #7 
May 2010
2^{2}·3 Posts 
should "verify results" be checked?

20100529, 04:13  #8  
May 2010
499 Posts 
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 redo the sieve.
Here's what the NewPGen contents file has to say about it: Quote:


20100530, 11:26  #9 
I quite division it
"Chris"
Feb 2005
England
31×67 Posts 
Hi
Approx. how long would it take to sieve 1T on 1 core of a Q6700 @ 2.66GHz? Chris 
20100530, 14:40  #10 
"Dave"
Sep 2005
UK
2×19×73 Posts 

20100530, 16:37  #11 
I quite division it
"Chris"
Feb 2005
England
31·67 Posts 
Okay, thanks.
Taking 4T5T. (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 3T4T. ) Off topic edit: (Hmmm. Time for me to find a new avatar.) Last fiddled with by Flatlander on 20100530 at 16:43 
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