[M]M36919[/M] has a 180.968bit (55digit) factor: [URL="https://www.mersenne.ca/M36919"]2997347544642661833497896836795494793702018162645139063[/URL] (P1,B1=2000000000,B2=401927737170960)
That gets me to the top of the [URL="https://www.mersenne.ca/userfactors/pm1/1/bits"]list of P1 factors for Mersenne numbers[/URL]! And all thanks to the new version 30.8 of mprime. :maybeso::wacky: 
:groupwave: :party:

Nice!

Wow! Congrats!

[QUOTE=nordi;606342] That gets me to the top of the [URL="https://www.mersenne.ca/userfactors/pm1/1/bits"]list of P1 factors for Mersenne numbers[/URL]! And all thanks to the new version 30.8 of mprime.[/QUOTE]
Congratulations! This comes in at 10th place on the [URL="https://members.loria.fr/PZimmermann/records/Pminus1.html"]alltime P1 list[/URL], i.e. not restricted to Mersennes. You should drop Paul Zimmermann an email; his address is on the page I linked. 
[QUOTE=charybdis;606354]This comes in at 10th place on the [URL="https://members.loria.fr/PZimmermann/records/Pminus1.html"]alltime P1 list[/URL], i.e. not restricted to Mersennes. You should drop Paul Zimmermann an email; his address is on the page I linked.[/QUOTE]Recordsize Mersenne factors are automatically reported to Paul Zimmerman (and Richard Brent for ECM) during the nightly data sync. The codepath for autoreporting P1 factors hasn't yet been tested (nobody has found a sufficiently large P1 factor since I wrote the code in 2020) so tonight will be its test. Wouldn't hurt for [i]nordi[/i] to email him anyways.

[QUOTE=storm5510;603269]This is from GMPECM, and an error on my part:
[CODE]********** Factor found in step 2: 223 20220404 09:43:03.243 Found prime factor of 3 digits: 223 20220404 09:43:03.243 Composite cofactor (2^73631)/223 has 2215 digits[/CODE] This is for M7363 which does not appear in any database I can find. I had intended M4363. Make of it what you will.[/QUOTE]Substantially beyond the limits of the 2 Cunningham table. Don't let that stop you from trying to find more factors though. 
[QUOTE=nordi;606342][M]M36919[/M] has a 180.968bit (55digit) factor: [URL="https://www.mersenne.ca/M36919"]2997347544642661833497896836795494793702018162645139063[/URL] (P1,B1=2000000000,B2=401927737170960)
That gets me to the top of the [URL="https://www.mersenne.ca/userfactors/pm1/1/bits"]list of P1 factors for Mersenne numbers[/URL]! And all thanks to the new version 30.8 of mprime. [/QUOTE] That is indeed a good factor! Crosspost it in the "([I]Preying for[/I]) World Record P1" thread :rolleyes: 
[QUOTE=xilman;606363]Substantially beyond the limits of the 2 Cunningham table.
Don't let that stop you from trying to find more factors though.[/QUOTE]For instance: [code] pcl@thoth:~/Astro/Misc$ ecm 10000 GMPECM 7.0.4 [configured with GMP 6.2.1, enableasmredc] [ECM] (2^73631)/223 Input number is (2^73631)/223 (2215 digits) Using B1=10000, B2=1678960, polynomial x^1, sigma=0:17348063569600894463 Step 1 took 838ms Step 2 took 724ms ********** Factor found in step 2: 4816405503271 Found prime factor of 13 digits: 4816405503271 Composite cofactor ((2^73631)/223)/4816405503271 has 2202 digits ((2^73631)/223)/4816405503271 Input number is ((2^73631)/223)/4816405503271 (2202 digits) Using B1=10000, B2=1678960, polynomial x^1, sigma=0:17644336739200299761 Step 1 took 833ms ********** Factor found in step 1: 616318177 Found prime factor of 9 digits: 616318177 Composite cofactor (((2^73631)/223)/4816405503271)/616318177 has 2193 digits [/code]That was, of course, rather silly. Because we know that 7363 = 37*199 there are some obvious algebraic factors. It was easier for me to type in ((2^73631)/223)/4816405503271 than to perform the algebra. 
[QUOTE=xilman;606367]For instance:
[code] pcl@thoth:~/Astro/Misc$ ecm 10000 GMPECM 7.0.4 [configured with GMP 6.2.1, enableasmredc] [ECM] (2^73631)/223 Input number is (2^73631)/223 (2215 digits) Using B1=10000, B2=1678960, polynomial x^1, sigma=0:17348063569600894463 Step 1 took 838ms Step 2 took 724ms ********** Factor found in step 2: 4816405503271 Found prime factor of 13 digits: 4816405503271 Composite cofactor ((2^73631)/223)/4816405503271 has 2202 digits ((2^73631)/223)/4816405503271 Input number is ((2^73631)/223)/4816405503271 (2202 digits) Using B1=10000, B2=1678960, polynomial x^1, sigma=0:17644336739200299761 Step 1 took 833ms ********** Factor found in step 1: 616318177 Found prime factor of 9 digits: 616318177 Composite cofactor (((2^73631)/223)/4816405503271)/616318177 has 2193 digits [/code]That was, of course, rather silly. Because we know that 7363 = 37*199 there are some obvious algebraic factors. It was easier for me to type in ((2^73631)/223)/4816405503271 than to perform the algebra.[/QUOTE]For an odd prime p, any prime factor q of 2^p  1 is of the form 2*k*p+1, k integer; in particular, q > p. This leads to a ludicrous proof of compositeness and factorization: The fact that 223 divides 2^7363  1 though 223 < 7363 proves that 7363 is composite. Factoring 223  1 or 222, we get the prime factors 2, 3, and 37. And 37 divides 7363, the quotient being 199. Curiously, the factor 4816405503271 divides the "primitive part" (2^7363  1)/(2^37  1)/(2^199  1) of 2^7363  1. The cofactor (2^7363  1)/(2^37  1)/(2^199  1)/4816405503271 is composite. 
[QUOTE=James Heinrich;606358]Recordsize Mersenne factors are automatically reported to Paul Zimmerman (and Richard Brent for ECM) during the nightly data sync. The codepath for autoreporting P1 factors hasn't yet been tested (nobody has found a sufficiently large P1 factor since I wrote the code in 2020) so tonight will be its test. Wouldn't hurt for [i]nordi[/i] to email him anyways.[/QUOTE]
I see that Paul's list still hasn't ben updated. Did the code work correctly? 
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