20220413, 11:00  #12 
Jun 2012
E36_{16} Posts 
XYYXF Remaining Composites
Here are the XYYXF composites as of April 2022.
One XYYXF is currently in GNFS by NFS@Home (C203_145_119) and has been omitted from the list. 
20220414, 14:00  #13  
Jun 2012
Boulder, CO
631_{8} Posts 
Quote:
http://factordb.com/index.php?id=1000000000044714162 http://factordb.com/index.php?id=1000000000044736161 

20220426, 15:18  #14 
Jun 2012
2×17×107 Posts 
XYYXF composites fully factored by Ryan Propper with ECM to date, shown as y_x_factor
Code:
95 138 137569872848618079168497788857665619070975508959085977 138 148 7148255126578794765422102122909172289268236979484218129 129 134 135670046698656711152317371191955389273883979954729787 111 139 2063202949990066743163751168921243267735542983816410497 81 146 103789758477794842211009755052743245746201848433761791953858611 124 141 133772128399353454302680369792367376604503532782027043821 148 149 164765011194494108378059619015812662809204025271338322937 118 148 3467745961171660748432832903372059871377664084616835703029 117 137 355804711213846224168595689144120149507294880133429929563 *136 150 633173149104321439701718688310849360699588006217613940817 122 145 95036826689253348122504549139573274683669492870863332268717 137 146 3118411803907757802223601737311246433663432677717416325331 129 140 43916092452583705950200190784289292829644462213724298857250903 123 134 8899027269008140316373707126027525152867402686853175806476907 Note that 149^148+148^149 was a SNFS difficulty of 323. Thank goodness for ECM! Last fiddled with by swellman on 20220426 at 15:22 
20220505, 01:00  #15  
"Curtis"
Feb 2005
Riverside, CA
5,381 Posts 
Quote:
Starting second one now. Haven't finished building the new desktop yet, which is why this is taking 3x as long as I expected. Last fiddled with by VBCurtis on 20220505 at 01:01 

20220505, 02:00  #16 
Jun 2012
7066_{8} Posts 
Thank you!

20220512, 13:17  #17 
Jun 2012
2×17×107 Posts 
Yoyo factored C222_141_82 with ECM @B1=260e6 when a p62 fell out. There is much fertile ground remaining for ECM in the XYYXF project at the higher levels (t60 and above).

20220525, 00:22  #18  
"Curtis"
Feb 2005
Riverside, CA
5,381 Posts 
Quote:
The third of four in the list was factored by yoyo; I'll work on #4 in a week or so when I finish ECM on 13_2_929m1. 

20220525, 00:58  #19 
Jun 2012
7066_{8} Posts 
Much appreciated!

20220612, 17:48  #20 
Jun 2012
2·17·107 Posts 
Ryan found a p70 in C251_131_128 using ECM with B1=850M. A remarkable find and 131^128+128^131 is fully factored to boot.
Code:
GMPECM 7.0.5dev [configured with GMP 6.2.0, GWNUM 30.4, enableasmredc, enableassert] [ECM] Due to incompatible licenses, this binary file must not be distributed. Input number is (128^131+131^128)/11993361557350502659918593 (251 digits) Using B1=850000000, B2=15892628251516, polynomial Dickson(30), sigma=1:2738913657 Step 1 took 2574357ms Step 2 took 597709ms ********** Factor found in step 2: 2396647352628340730333265310821035979852802473169960235597808820903739 Found prime factor of 70 digits: 2396647352628340730333265310821035979852802473169960235597808820903739 Prime cofactor ((128^131+131^128)/11993361557350502659918593)/2396647352628340730333265310821035979852802473169960235597808820903739 has 182 digits 
20220701, 01:27  #21 
Jun 2012
3638_{10} Posts 
Ryan got another big hit, finding a p68 in C238_149_79, followed by GNFS to crack the C172 cofactor (p88 * p83).
Both this factor and the p70 he found in 131^128+128^131 (see prior post) are both in the top 10 factors of 2022 despite using a B1 value of only 850e6 in both cases. 
20220721, 12:52  #22 
Jun 2012
2×17×107 Posts 
Update
296 Composites remain in the 1 < y < x < 151 XYYXF project.
292 SNFS composites  4 are enqueued with NFS@Home  10 have reached t65+ (these are the remaining C300+ composites). They are extremely difficult to sieve.  278 have only reached t55 to date. All need at least t60, most need more. 4 GNFS composites Code:
C203_147_104 C204_147_118 C195_145_122 C211_147_145 C195_145_122 fell out of the sky as a composite cofactor after ECM found a p59. It is now being preprocessed by Yoyo. C211_147_145 was recently identified as a GNFS job. Test sieving of its SNFS 298 septic polynomial (best of the lot) showed low yield and speed vs sieving performance of a previously factored GNFS 211. But it needs a LOT of ECM. As with most current factoring projects, the 280 XYYXF composites needing ECM is the most pressing concern. At Yoyo’s current production rate, a single pass of 20,000 curves @B1=260M would take 68 years to complete. So any individual efforts would be greatly appreciated and welcome! A shout out to Ryan for maintaining his ECM efforts on XYYXF. 
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