20200522, 07:46  #496 
(loop (#_fork))
Feb 2006
Cambridge, England
2·11·17^{2} Posts 
L4375B done
This popped up on the Mersennus.net page and I managed to complete it in three realtime weeks on one machine (I'll admit it was an i97940X so quite a fast machine)  2.5 days polynomial search, a bit of a gap while other jobs finished and I did the trial sieving, 12 days sieving, 1 day linear algebra.
32bit LP, three algebraic large primes, alim=rlim=5e7, sieve Q=25M75M (which is nice and round, but was determined by looking at yields incrementally rather than entirely in advance) Notice how smooth the yield curve is when corrected for ideal count, and how the peak here is at alim. With this extra smoothness reasonablesized trial sieving gives much more credible numbers; I'm not sure I'd have used 3lpa for things this small but it was clearly several percent better in the trialsieve. Expecting baby before next factor :) Last fiddled with by fivemack on 20200522 at 07:47 
20200525, 15:33  #497  
Sep 2009
3×631 Posts 
Quote:
Code:
522 Special q, 3933 reduction iterations Thanks in advance. Chris 

20200611, 16:51  #498 
Apr 2020
2×47 Posts 
Lucky ECM hit, from 3+2_1842M from the HCN tables:
Code:
GMPECM 7.0.5dev [configured with GMP 6.2.0, enableasmredc, enableassert] [ECM] Input number is 2575167245145580345545358603140126953887375815021234731765984191692079396591260156613577262910448277094539273838808805370857935219624918675016962379584174887505043190773944811610010073257320929688633424357191886761888329736734042381290881 (238 digits) Using B1=110000000, B2=776278396540, polynomial Dickson(30), sigma=1:2166799276 Step 1 took 304804ms Step 2 took 88190ms ********** Factor found in step 2: 1881941120468249708169539576246651193369513480043229827729929343069 Found prime factor of 67 digits: 1881941120468249708169539576246651193369513480043229827729929343069 Prime cofactor 1368356967780611326835948661781737382237519565564396399185048685206843247071058939238469661163518378115591947475004902031363212895011322108712962118435289831026432120434549 has 172 digits 
20200905, 09:00  #499 
"Alexander"
Nov 2008
The Alamo City
375_{10} Posts 
This is (AFAIK) my personal ECM record:
122760214563986517403408012718327323026952918039831060056060998708807150488395908248657867219215800100789370303292314531669 = 85548851675281967428710863747045885644186850007163 * 1434972090916519038274518487801044320499147038941606461183097450445450863 (21^76:i208). This P50 was found in just 410 curves at B1=3M. I lack patience and my hardware is really old, so this saved the sequence from exceeding the selfimposed C120 cofactor limit for NFS. 
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