20200522, 07:46  #496 
(loop (#_fork))
Feb 2006
Cambridge, England
6323_{10} 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
5·389 Posts 
Quote:
Code:
522 Special q, 3933 reduction iterations Thanks in advance. Chris 

20200611, 16:51  #498 
Apr 2020
2×3×19 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
3×137 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. 
20201011, 10:40  #500 
May 2009
Russia, Moscow
23×109 Posts 
Really lucky hit for aliquot sequence 79^91:i5
Code:
GMPECM 7.0.4 [configured with GMP 6.1.2, enableasmredc] [ECM] Input number is 265068640573758407535905984867282858553267450389668652958394878324092361572221738127508595352727313041526471350792042955118039583885472232715529 (144 digits) ... Run 12 out of 150: Using B1=43000000, B2=240490660426, polynomial Dickson(12), sigma=1:734709831 Step 1 took 143604ms Step 2 took 52384ms ********** Factor found in step 2: 10622969779722833224233821696670456635150835905540542178233981211 Found prime factor of 65 digits: 10622969779722833224233821696670456635150835905540542178233981211 Prime cofactor 24952404654273090201857266161762430747111830388231810834477663075621591193735339 has 80 digits 
20201020, 17:17  #501 
"Daniel Jackson"
May 2011
14285714285714285714
613 Posts 
Lucky ECM find
P43 factor of C88 found by ecm.
Code:
ecm: 64/150 curves on C88, B1=250K, B2=gmpecm default, ETA: 21 sec ecm: found prp43 factor = 2142249281864552971319672366351205960114907 ecm: 67/150 curves on C46, B1=250K, B2=gmpecm default, ETA: 21 sec fac: setting target pretesting digits to 14.15 t15: 51.14 t20: 19.60 t25: 2.39 t30: 0.22 t35: 0.02 fac: estimated sum of completed work is t26.11 fac: QS time estimation from tune data = 0.05 sec fac: GNFS time estimation from tune data = 10.29 sec pretesting / qs ratio was 4886.50 Total factoring time = 39.3250 seconds ***factors found*** P43 = 2142249281864552971319672366351205960114907 P46 = 1074732871675494834696515187318946620981020017 ans = 1 Last fiddled with by Stargate38 on 20201020 at 17:18 Reason: fix typo 
20201020, 17:31  #502  
"Ben"
Feb 2007
13×257 Posts 
Quote:


20201103, 11:21  #503 
Aug 2015
1000000_{2} Posts 
EuclidMullin EM46 C215 ECM
Log:
Code:
Using B1=260000000260000000, B2=3178559884516, polynomial Dickson(30), sigma=3:957017298 Step 1 took 0ms Step 2 took 493313ms ********** Factor found in step 2: 15124628508282822860728592244514109925406256499230092227643 Found probable prime factor of 59 digits: 15124628508282822860728592244514109925406256499230092227643 Probable prime cofactor 4014473321008880083061629862535686360557015504856646058591888394131533153312046292751100693592725892009103700653633441678523812403799240000868489865492195879 has 157 digits 
20201103, 20:06  #504 
Aug 2004
New Zealand
2^{2}·5·11 Posts 
Congratulations. For a moment I thought you had done the leading edge, but it is still nice to have this one done as well. So I see EM49 is now the smallest not completely factored number in this line (and EM52 of course).

20201111, 22:59  #505  
Jan 2012
Toronto, Canada
2^{2}×11 Posts 
Lucky find of the month:
Quote:


20201112, 09:48  #506 
"Oliver"
Sep 2017
Porta Westfalica, DE
2^{4}×23 Posts 
Code:
Expected number of curves to find a factor of n digits: 35 40 45 50 55 60 65 70 75 80 1071 10283 118226 1565171 2.4e+07 3.9e+08 7.7e+09 2.9e+11 5.6e+16 7.6e+21 
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