20180817, 13:19  #452 
Jul 2018
19 Posts 
ECM on a C213, the last divisor of (34*10^22961)/9 with sigma=1:3941682105:
Using B1=2900000000, B2=82640965106716, polynomial Dickson(30), sigma=1:3941682105 [...] ********** Factor found in step 2: 35020442769329876367522852735060830348867981850170604303099578467 Found prime factor of 65 digits: 35020442769329876367522852735060830348867981850170604303099578467 Prime cofactor 6463948784722816185901384621852688761921664616020783901443547268726228461664676485561963639543974467240297445194995726733180417921657435498535243769 has 148 digits The factor was found on the 25th curve; taking into account all the other cores running curves this was the 2400th curve of only 9600 I planned to run before handing the problem to CADONFS, so I'm counting myself quite lucky! 
20180817, 13:49  #453  
Banned
"Luigi"
Aug 2002
Team Italia
11·433 Posts 
Quote:


20180818, 19:49  #454 
Sep 2002
Vienna, Austria
DB_{16} Posts 
Code:
Input number is (109^1231)/(109^411)/95898591887152691733740679 (142 digits) Using B1=43000000, B2=240490660426, polynomial Dickson(12), sigma=1:3742107819 Step 1 took 66545ms Step 2 took 23004ms ********** Factor found in step 2: 113910660004153337924628664386678247208828533 Found prime factor of 45 digits: 113910660004153337924628664386678247208828533 Prime cofactor ((109^1231)/(109^411)/95898591887152691733740679)/113910660004153337924628664386678247208828533 has 98 digits 
20180916, 17:54  #455 
"Jane Sullivan"
Jan 2011
Beckenham, UK
232_{10} Posts 
C135 from 1208^47+1:
Code:
prp43 = 7872050983542095687417246190511880248639711 prp92 = 16940363046999582482928413622346911064605327855533940683539949731286830685125532654826597073 Code:
prp38 = 98345853344307565253324824092518095601 prp87 = 929528781257601652853545435226628885326214271769204819819291780270828421426874911996487 
20181210, 13:54  #456 
(loop (#_fork))
Feb 2006
Cambridge, England
14321_{8} Posts 
L3780 factored
199digit GNFS, done entirely locally
Code:
N 1253697014483921701519774710080293856978446067093422585355224278757029355514329819946916985971979863264272814638205843444068083099253312799641803553719988196912895006268194994880801257942554688556001 SKEW 127028183.52 A0 595638964036345481237071140491743854143245809544 A1 29926818433789606747718647951662435504208 A2 307924512754708078991927303315680 A3 4781679268252586458599169 A4 22400530233973836 A5 102927636 R0 104023657306189391164144906961130612015 R1 651664577069232468431 Code:
lpbr: 33 lpba: 33 mfbr: 66 mfba: 96 alambda: 3.5 rlambda: 2.4 alim: 268000000 rlim: 268000000 Code:
Tue Nov 13 07:30:38 2018 matrix is 48788680 x 48788857 (23378.5 MB) with weight 7047295017 (144.44/col) Tue Nov 13 07:30:38 2018 sparse part has weight 5543070617 (113.61/col) Tue Nov 13 07:40:47 2018 filtering completed in 2 passes Tue Nov 13 07:40:57 2018 matrix is 48786801 x 48786976 (23378.4 MB) with weight 7047214552 (144.45/col) Tue Nov 13 07:40:57 2018 sparse part has weight 5543053801 (113.62/col) Tue Nov 13 07:43:08 2018 matrix starts at (0, 0) Tue Nov 13 07:43:15 2018 matrix is 48786801 x 48786976 (23378.4 MB) with weight 7047214552 (144.45/col) Tue Nov 13 07:43:15 2018 sparse part has weight 5543053801 (113.62/col) Tue Nov 13 07:43:15 2018 saving the first 240 matrix rows for later Tue Nov 13 07:43:27 2018 matrix includes 256 packed rows Tue Nov 13 07:43:42 2018 matrix is 48786561 x 48786976 (21440.4 MB) with weight 5118664178 (104.92/col) Tue Nov 13 07:43:42 2018 sparse part has weight 4839889639 (99.20/col) Tue Nov 13 07:43:42 2018 using block size 8192 and superblock size 473088 for processor cache size 19712 kB Tue Nov 13 07:45:56 2018 commencing Lanczos iteration (14 threads) Tue Nov 13 07:45:56 2018 memory use: 29766.8 MB Tue Nov 13 07:47:23 2018 linear algebra at 0.0%, ETA 637h43m Tue Nov 13 07:47:47 2018 checkpointing every 80000 dimensions Mon Dec 10 04:01:57 2018 lanczos halted after 191142 iterations (dim = 48786558) Mon Dec 10 04:05:48 2018 recovered 29 nontrivial dependencies Mon Dec 10 04:06:03 2018 BLanczosTime: 2324842 Mon Dec 10 04:06:03 2018 elapsed time 645:47:23 Code:
Mon Dec 10 12:47:23 2018 p82 factor: 9214409416745614101198894993721726856303159042273240016125104117470329343249250561 Mon Dec 10 12:47:23 2018 p117 factor: 136058314513954814229280792975681347764936790375643059794253062274788902853667069820292458749493930656793985621603041 Last fiddled with by fivemack on 20181210 at 14:15 
20190102, 17:36  #457 
May 2009
Russia, Moscow
100110010011_{2} Posts 
59digit factor of nearrepdigit (691*10^{300}7)/9 was found by ECM
Code:
Using B1=43000000, B2=240490660426, polynomial Dickson(12), sigma=3032066922 Step 1 took 382110ms Step 2 took 101223ms ********** Factor found in step 2: 21601138366813705693033870951386003818115059066377541324921 Found probable prime factor of 59 digits: 21601138366813705693033870951386003818115059066377541324921 Composite cofactor 1416732463683710775182530542771135815901595515342842856966117614129678227859411077172659990398292541537568243400899333336769174248499204974915626874899 has 151 digits 
20190102, 18:10  #458  
"Ben"
Feb 2007
CCC_{16} Posts 
Quote:


20190107, 07:18  #459 
"Victor de Hollander"
Aug 2011
the Netherlands
2^{3}·3·7^{2} Posts 
Code:
P1 found a factor in stage #2, B1=2000000, B2=40000000, E=6. M55715311 has a factor: 7239753241433926010086285741758451306831 (P1, B1=2000000, B2=40000000, E=6) 
20190111, 22:48  #460 
1976 Toyota Corona years forever!
"Wayne"
Nov 2006
Saskatchewan, Canada
10EF_{16} Posts 
Factored twin primes

20190112, 05:28  #461 
Romulan Interpreter
Jun 2011
Thailand
21BB_{16} Posts 
not really twins (difference of 10), and generally, you can't factor a prime...

20190112, 07:05  #462 
"Sam Laur"
Dec 2018
Turku, Finland
144_{16} Posts 
Heh. Which sort of reminds me, I kinda shot myself in the foot a week ago. I was LL double checking a few exponents and decided to run TF a bit further just for the heck of it ...and found a factor on one of them. Some CPU time wasted, but more saved, as it wasn't even halfway through at that point.
M51202189 It even had some (old? low bounds?) P1 work done on it, but then again, mersenne.ca says that min. B1 is 20,857 and min. B2 10,925,329,931 so maybe it was just one of those hard to find factors. 
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