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 2022-01-18, 16:51 #2036 Luminescence   Oct 2021 Germany 32×11 Posts 10404679: 118793848017180226139209650887 (30 digits, 96.584 bits) This looks like any old factor... until you take a look at the effort required for this one. Normal P-1 is at 1,069.7 GHz-days and the min. bounds are B1=597,137 and B2=22,193,557,699 Bless version 30.8
 2022-01-20, 14:26 #2037 Xyzzy     Aug 2002 33·313 Posts 10713539 M10713539 has a factor: 9646618965808297396650789217449140593554849484807561 (P-1, B1=3000000, B2=21676825170) 7259945416488565152965177 × 1328745384765454647667709393
 2022-01-20, 17:46 #2038 bur     Aug 2020 79*6581e-4;3*2539e-3 503 Posts It was suggested that ECM often makes more sense on those smaller Mersenne than P-1, and yes, there are a lot of low-hanging fruits with t35 done only partially. 1500 B1=1M curves on a 10 core take about 1.5 days and you can be fairly certain you won't miss any factor < 35 digits with that. Code: First hit: M177949 Factor: 33673305014952064901960880605783657 (35 digits) ECM B1=1000000, B2=167000000, Sigma=3976350787451175 k = 2^2 × 7 × 113 × 29903617016456689669335223 (boom, take that, P-1) Group order: 2^4 × 3 × 251 × 3319 × 26111 × 111767 × 477073 × 741043 × 816203 Don't take this too serious, I did a lot of P-1 and even P+1 and I definitely get the lottery appeal of it with the chance to score big... :)
 2022-01-21, 20:39 #2039 petrw1 1976 Toyota Corona years forever!     "Wayne" Nov 2006 Saskatchewan, Canada 120758 Posts 3 in a row via P1. Code: Magic_8_Ball 20824319 NF-PM1 2022-01-21 14:35 0.0 B1=800000, B2=288897180 19.4015 Magic_8_Ball 20824147 F-PM1 2022-01-21 14:17 0.0 Factor: 495235256819022693269729 / (P-1, B1=800000, B2=288897180) 19.4015 Magic_8_Ball 20823619 F-PM1 2022-01-21 13:58 0.0 Factor: 25548786609611112273299959 / (P-1, B1=800000, B2=288897180) 19.4015 Magic_8_Ball 20820379 F-PM1 2022-01-21 13:40 0.0 Factor: 1046110442462024597648707729 / (P-1, B1=800000, B2=288897180) 19.4015 Magic_8_Ball 20818361 NF-PM1 2022-01-21 13:21 0.0 B1=800000, B2=288897180 19.4015
 2022-01-22, 20:29 #2040 Flaukrotist   Sep 2020 Germany 43 Posts M8180143 has a 210.388-bit (64-digit) composite (P25+P39) factor: 2153365510583437050044092603818787130235731554764189688651981753 (P-1,B1=1500000,B2=800578350) Yeah, my first double factor in one P-1 attempt. And it includes the largest factor, I found so far (#172 in the Top P-1 factor list).
 2022-01-24, 12:05 #2041 Jan S   Oct 2018 Slovakia 10010 Posts ECM found a factor 104297 B1=3000000, B2=447000000, curve 244 33730663290433956450015516054234200283383287 144.597 bits
 2022-01-30, 20:09 #2042 firejuggler     "Vincent" Apr 2010 Over the rainbow 2·3·11·43 Posts M14691419 has a 148.225-bit (45-digit) composite (P23+P23) factor: 416943345784701035645026212406037518765877617 (P-1,B1=2100000,B2=534604980) both are 74 bits
 2022-01-31, 10:49 #2043 bur     Aug 2020 79*6581e-4;3*2539e-3 1F716 Posts Code: M21013 Factor: 262993879056590526599462437387619513220841 (42 digits, 137.6 bits) B1=3000000, B2=528000000, Sigma=6108330422011107 Group order = 2^2 x 3^5 x 11 x 263 x 643 x 19157 x 20071 x 63331 x 147881 x 652601 x 61893779 k = 2^2 x 3 x 5 x 59 x 242399 x 7292786486304502390480104379 It's the third factor of M21013 (1.56%), remaining co-factor is composite. That factor could have quite likely been found with B1=1M already. Last fiddled with by bur on 2022-01-31 at 10:53
 2022-02-02, 01:58 #2044 Zhangrc   "University student" May 2021 Beijing, China 2·53 Posts Simon Josefsson has found a factor (7th biggest!) M108366469 has a factor: 21806524243495451887372970600275462563390077239 (153.933 bits) Congratulations!
 2022-02-03, 00:41 #2045 chalsall If I May     "Chris Halsall" Sep 2002 Barbados 101000110011102 Posts Maybe this means I should buy some lottery tickets??? You have to love statistics... Code: gpu72ng 11757341 F-PM1 2022-02-03 00:05 6.4 Factor: 18209030934069669978769 / (P-1, B1=2000000, B2=496384980) 18.6152 gpu72 11765911 F-PM1 2022-02-02 23:09 4.3 Factor: 813514493428352514799942217 / (P-1, B1=2000000, B2=496384980) 18.6152 gpu72ng 11757293 F-PM1 2022-02-02 23:03 6.3 Factor: 287095610823108514130103097 / (P-1, B1=2000000, B2=496384980) 18.6152
 2022-02-04, 07:58 #2046 bur     Aug 2020 79*6581e-4;3*2539e-3 7678 Posts M22621 has a third factor: Code: 140986430775391680242875594970278954759 (39 digits, 126.7 bits) ECM, B1=3M, B2=321M, Sigma=3634941837045978 k = 3^3 × 71 × 31481 × 317371 × 5654288209 × 28775289833 I had trouble with the group order though, it had 17 and 18 digits factors which doesn't agree with the B1/B2 bounds. Switching to parameter=1 didn't help. Does anyone know what I did wrong?

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