|Sunday, February 17th, 2013. MSieve
Tuesday, December 11th, 2012. 86562929 + 29298656, a number with 30008 decimal digits, was proven prime by Jens Franke et.al. with a new algorithm called CIDE breaking the world record in general purpose primality proofs. Two more probable primes were reserved, with more than 50k and more than 100k decimal digits respectively.
Monday, November 12th, 2012. No composites left with less than 154 digits. Thanks to Sean Wellman and his GNFS efforts.
Tuesday, June 26th, 2012. The total number of the composites was reduced to 1300.
Saturday, May 12th, 2012. The concept of "wanted composites" vanished.
Wednesday, April 25th, 2012. Sean A. Irvine found a 99-digit prime factor of 13064 + 64130, setting up a new record. It took just 10 days to make the factorization, but more than three years to beat the previous record.
Sunday, July 24th, 2011. The total number of the composites was reduced to 1400.
Monday, May 30th, 2011. All the composites passed ECM tests with B1 = 11M.
Monday, May 2nd, 2011. The ECM server retired from the work after nine years of activity. Great thanks to Greg Childers who maintained the server for such a long time.
Thursday, March 31st, 2011. The total number of the composites was reduced to 1500.
Friday, February 18th, 2011. A probable prime with more that 300k digits, 3147389 + 9314738, is found by Anatoly Selevich. Congratulations to him!
Saturday, November 13th, 2010. The total number of the composites was reduced to 1600.
Wednesday, June 30th, 2010. All the numbers up to x = 105 inclusively had been completely factored.
Wednesday, June 9th, 2010. Göran Hemdal reported that three PRPs, 3782315 + 3153782, 3784315 + 3153784 and 37892932 + 29323789, were missing from the Primes page. Thanks to Göran for double-checking the computations!
Sunday, April 11th, 2010. The total number of the composites was reduced to 1700.
Monday, December 7th, 2009. Two new GNFS records, at 150 and at 151 decimal digits, were established by the powerful RSALS sieving grid with a help of Lionel Debroux and Jeff Gilchrist. Both huge tasks took only 8 calendar days to complete. Congratuations to the RSALS team!
Wednesday, November 25th, 2009. The total number of the composites was reduced to 1800. Quite a speed.
Thursday, November 19th, 2009. No prime factors of 12293 + 93122 were known until Greg Childers factored this really huge number with SNFS, setting up an SNFS record at 241 digits which is quite hard to beat. This just reminded me a seven years older 188-digit SNFS record by Paul Leyland. At that time, in 2002, it was unbelievable that a 195-digit SNFS job would not fit the Top-20. But with Greg's new result the last C195 fell out of the table.
Thursday, August 20th, 2009. The total number of the composites was reduced to 1900.
Tuesday, June 23rd, 2009. The list of the wanted composites was significantly expanded due to Greg Childers' SNFS efforts. :-) About 170 new numbers were added, preferably with smaller x's and SNFS difficulty < 200.
Monday, April 27th, 2009. The total number of the composites was reduced to 2000. That's an ECM attack!
Monday, February 16th, 2009. Jeff Gilchrist published a nice Beginners Guide to NFS factoring using GGNFS and Msieve to help newcomers with applying GNFS and SNFS tools.
Tuesday, January 27th, 2009. The total number of the composites was reduced to 2100. The 2k milestone is definitely reachable within 2009.
Monday, January 5th, 2009. Serge Batalov factored 12465 + 65124 just in 10 days, setting up two XYYXF records, for the largest prime factor (96 digits) and for the largest factorization (225 digits). By the way, no prime factors of this number were previously known. Congratulations again Serge!
Friday, June 6th, 2008. A new page, Primes and PRPs of the form xy + yx, appeared on our site. These tables were originally maintained by Paul Leyland, but became outdated with time, so there's a new version, somehow revised and supplemented with the latest results.
Thursday, May 1st, 2008. The total number of the composites was reduced to 2200. We're getting quicker :-)
Sunday, October 28th, 2007. All the numbers up to x = 100 inclusively had been completely factored. It's a real milestone! Almost 6 years had been passed since there numbers were involved in the project. Greetings go out to our contributors, and especially to Greg Childers and Sean A. Irvine who worked purposely on the x < 101 numbers all this time. Well done people!
Thursday, October 18th, 2007. The total number of the composites was reduced to 2300. A good rate!
Wednesday, September 5th, 2007. All the numbers up to x = 95 inclusively had been completely factored.
Wednesday, August 29th, 2007. All the numbers up to x = 100 were included in the wanted list.
Sunday, September 10th, 2006. The total number of the composites was reduced to 2400. You see, the speed of the factoring process became as low as exactly one hundred per year. The next hundred of composites will probably take several years...
Wednesday, November 2nd, 2005. Three lost factorizations were restored. All of them were made by Larry Soule more than 3 months before but unfortunately I missed them at the time.
Saturday, September 10th, 2005. The number of the composites was reduced to 2500.
Saturday, June 18th, 2005. MSieve 1.0 was released.
Wednesday, June 1st, 2005. Please upgrade
your ECM client to version 2.6.1.
Wednesday, April 27th, 2005. All the numbers with y < 16 had been completely factored.
Sunday, March 27th, 2005. Don Leclair factored a 200-digit composite number with SNFS. It was a cofactor of 10389 + 89103. This awesome job took 35 days: twenty days of sieving, two weeks of linear algebra, a few hours of square root phase. And result is excellent: C200_103_89 = P95*P105. Congratulations to Don!
Wednesday, March 16th, 2005. All the numbers up to x = 90 inclusively had been completely factored.
Wednesday, March 16th, 2005. A serious bug in the ECM client was fixed, so please upgrade the program.
Friday, March 4th, 2005. The number of the composites was reduced to 3000.
Monday, February 28th, 2005. This month was amazing. 112 factorizations were reported, and most of the numbers were taken from the wanted list, while all remaining composites with x < 91 became reserved. Therefore 56 new composites (x from 91 to 95) were added to the wanted list. If all these additions had been made at once in the beginning of the year, there would have been 274 (!) wanted numbers. But, you see, almost a half of them had been factored just in two months.
Monday, February 28th, 2005. GMP-ECM 6.0 was released. This version has many improvements, e.g. speed-up in step 2 (especialy for large values of B2).
Monday, February 7th, 2005. Three days passed, and suddenly Hartmut Bock factored 108100 + 100108 making a seven-digit improvement to his recent P-1 result. This huge P49 divisor became the 4th largest prime factor found so far by P-1 method in the world.
Monday, February 7th, 2005. All the numbers with y < 11 had been completely factored.
Tuesday, February 2nd, 2005. A massive SNFS attack caused me to change my decision about the wanted list. So, 38 new numbers appeared there, it should be enough.
Friday, January 28th, 2005. An SNFS task, at 152 decimal digits, was successfully completed by Samuel Chong using GGNFS. To say the truth, the project was really reanimated due to this excellent software written by Chris Monico.
Wednesday, January 13th, 2005. The ECM client was updated to version 2.5.6 released by Mark Rodenkirch on the 3rd of January. Please download the new version and use it instead of an old one.
Thursday, December 30th, 2004. The set of wanted composites was extended to 180 numbers to provide wider choice for ECM and GNFS tasks. The list became too long, but I thought I wouldn't add more until 2006.
Monday, December 27th, 2004. The e-mail address of the project was changed due to some technical problems. Please use the new address: XYYXF@mail.by.
Monday, December 13th, 2004. The composite number of 130 digits was factored by Sean A. Irvine in 10 days with GNFS. Thus Sean completed the factorization of 8780 + 8087 and established a new GNFS record yet another time.
Tuesday, November 23rd, 2004. An alternative SIQS program, MSieve by Jason S. Papadopoulos, began to be used by our contributors. Version 0.83 was released and appeared to be quite fast, especially on AMD processors.
Wednesday, November 17th, 2004. A new open-source GNFS implementation, GGNFS by Chris Monico, had been quickly developed. The program became faster and more stable (GGNFS 0.70.0 was the latest version by the moment). Feel free to join the GGNFS Yahoo! group where you can help to test this software and to discuss it with other users.
Tuesday, July 6th, 2004. Paul Leyland's page Primes and PRPs of the form xy + yx (as well as other pages from Paul's site) was moved to the new location: http://www.leyland.vispa.com/numth/primes/xyyx.htm.
Thursday, May 20th, 2004. Sean A. Irvine, the main record holder of our project, completed the factorization of 8669 + 6986, the last number with x under 87, using GNFS method. It took 11 days to split the 124-digit composite cofactor establishing a new GNFS record. It must be also noted that this entry completed the Top-20 of GNFS records, so the total number of record entries reached 100, and therefore, in the end, all five record tables became filled. And since we have so many great news in one day, let me add another one, altough it's a bit off-topic... There was a birthday of my little niece Svetlana, she was two! :)
Saturday, March 27th, 2004. Hartmut Bock took all remaining composites (i.e. with x < 101) to run P±1 tests with B1 = 1G.
Thursday, February 5th, 2004. Richard Heylen started running P±1 tests using B1 = 1G over all XYYXF composites with x > 100 and quickly found a 42-digit prime factor of 136107 + 107136, setting a new P-1 record.
Thursday, December 11th, 2003. All the numbers up to x = 85 inclusively had been completely factored.
Friday, November 7th, 2003. Paul Zimmermann and Alexander Kruppa reported a bug in GMP-ECM which makes versions 5.0, 5.0.1 and 5.0.2 miss some factors. Please upgrade your version of GMP-ECM to 5.0.3 (or newer).
Monday, November 3rd, 2003. Greg Childers discovered some new algebraic factorizations of xy + yx using Mathematica. Namely, he factored y = 35 and 77 for x = 112; x = 133 and 147 for y = 112; x = 115 and 145 for y = 100 as well as the following pairs (x, y): (150, 24); (133, 28); (133, 76) and (147, 36). If the corresponding composites were factored with sieving methods, it would have taken weeks of CPU time.
Saturday, August 23rd, 2003. The number of the composites was reduced to 3500.
Monday, August 18th, 2003. Richard Heylen finished P±1 tests with B1 = 100M for all composites.
Friday, May 9th, 2003. The Top-20 of P±1 factors was quickly filled by Richard Heylen and several other contributors.
Sunday, April 27th, 2003. Greg's server finished running ECM with B1 = 250000.
Monday, February 24th, 2003. The new version of GMP-ECM program was released. A lot of new features were added in version 5.0, such as P±1 implementations and much faster B2 stage. Great thanks to Paul Zimmermann, Alexander Kruppa, Jim Fougeron and many other GMP-ECM contributors.
Friday, February 21st, 2003. Two days passed, and Sean A. Irvine improved his own GNFS result yet again, one digit longer and one day quicker. By the way, that new top-GNFS number became larger than the top-QS one.
Sunday, January 5th, 2003. All the numbers up to x = 80 inclusively had been completely factored.
Thursday, December 26th, 2002. The number of composites with x < 101 was reduced to 300.
Wednesday, November 27th, 2002. The final pre-factoring stage was started on the numbers with 100 < x < 151. Greg Childers and Paul Leyland took the most of numbers to help.
Tuesday, October 22nd, 2002. The largest XYYXF composite, 188-digit number 9881 + 8198, was factored by Paul Leyland with SNFS, yielding a 79-digit prime factor. Sieving took more than a month with the power of up to 32 CPU's. Several CPU-days were necessary to run the filtering stage and to produce the matrix of the size about 3Mx3M. Linear algebra was done on a single machine in 20 days and took 793 Mb of RAM. Finally, the square root stage just in an hour completed this great job. Paul's SNFS record will stay on the 1st place until the project is extended and somebody choose a larger number to beat it.
Thursday, August 29th, 2002. The Top-20 of ECM records was completely filled. Greetings went out to Greg Childers, Pierrick Gaudry and many other contributors.
Friday, August 23rd, 2002. Andrey Kulsha started factoring XYYXF numbers up to x = 150.
Monday, August 19th, 2002. All the numbers up to x = 75 inclusively had been completely factored.
Friday, July 19th, 2002. The number of the composites was reduced to 400.
Wednesday, July 10th, 2002. And the Top-20 of largest QS-factored XYYXF composites was also filled. Most of the records belongs to Don Leclair whose SIQS implementation is quite fast.
Tuesday, June 25th, 2002. The Top-20 of largest SNFS-factored XYYXF composites was filled completely, from 1st rank to 20th. Thanks to Sean A. Irvine for his great SNFS effort.
Friday, June 21st, 2002. All the numbers up to x = 70 inclusively had been completely factored.
Tuesday, May 28th, 2002. The number of the composites was reduced to 500.
Wednesday, May 15th, 2002. And another ECM record by Pierrick Gaugry: he extracted a huge 48-digit prime factor from 6932 + 3269. This GMP-ECM factor appeared to be the largest one found so far in 2002.
Saturday, March 30th, 2002. The number of
the composites was reduced to 600.
Sunday, March 24th, 2002. Jens Franke released the new version of his excellent MPQS implementation for Linux which is believed to be yet faster than PPSIQS. It was tested with numbers having up to 124 digits.
Tuesday, March 19th, 2002. All the numbers up to x = 60 inclusively had been completely factored.
Wednesday, March 13th, 2002. The number of the composites was reduced to 750.
Sunday, January 27th, 2002. The number of the composites was reduced to 1000.
Friday, December 28th, 2001. Paul Leyland became the first contributor of XYYXF and greatly speeded up factoring process with the help of several machines.
Friday, November 23rd, 2001. All the numbers up to x = 100 were involved into factoring process.
Wednesday, November 14th, 2001. All the numbers up to x = 50 inclusively had been completely factored.
Friday, November 9th, 2001. Satoshi Tomabechi released the new version of PPSIQS which works faster than previous.
Tuesday, October 30th, 2001. Andrey Kulsha started factoring numbers of the form xy + yx for x < 61 on his slow AMD K6-233...