Let n be a prime number with 500 < n < 1000.
I'm planning on doing some ECM on the numbers 17[SUP]n[/SUP]-1.
For n=503, I did 7100@3e8 back in 2014/2015.
For n>503, I'll begin with a t35. I found three factors:
P33 for [URL="http://factordb.com/index.php?id=1000000000048520545"]17^521-1[/URL]
P32 for [URL="http://factordb.com/index.php?id=1000000000048520547"]17^523-1[/URL]
P29 for [URL="http://factordb.com/index.php?id=1000000000048520953"]17^929-1[/URL]


Note: exponents 563, 577 and 683 are excluded from this effort for
the moment because Ryan did some effort on them (maybe a t50
since a 49 digits factor has been found for 17^577-1) since they
are in mwrb2100.txt.

[QUOTE=YuL;565270]Let n be a prime number with 500 < n < 1000.
I'm planning on doing some ECM on the numbers 17[SUP]n[/SUP]-1.[/QUOTE]It might be faster for these numbers to run stage 1 ECM with prime95, and only run stage 2 with GMP-ECM. It was definitely faster for me when I was running 10^999+13.

[QUOTE=lavalamp;565385]It might be faster for these numbers to run stage 1 ECM with prime95, and only run stage 2 with GMP-ECM. It was definitely faster for me when I was running 10^999+13.[/QUOTE]


Thanks, I used to do that... Now I just run a GMP-ECM linked with GWNUM
and it does the job :)


[CODE]GMP-ECM 7.0.4 [configured with GMP 6.1.2, [B]GWNUM 29.8[/B], --enable-asm-redc] [ECM]
Tuned for x86_64/k8/params.h
Due to incompatible licenses, this binary file must not be distributed.
Input number is (17^509-1)/(2^4*1019*10181*27487*91621) (609 digits)
[B]Found number: 1*17^509 + -1[/B]
[Sat Dec 5 22:00:48 2020]
Using mpz_mod
Using B1=3000000, B2=4592487916, polynomial Dickson(6), sigma=0:16358333240206248675
dF=14400, k=2, d=150150, d2=17, i0=3
Expected number of curves to find a factor of n digits:
35 40 45 50 55 60 65 70 75 80
336 2462 21289 210320 2370354 3e+07 4.2e+08 6.4e+09 1.2e+11 9.6e+15
[B]Using gwnum_ecmStage1(1, 17, 509, -1, 3000000, 1)[/B]
Step 1 took 23068ms
Estimated memory usage: 194.24MB
Initializing tables of differences for F took 68ms
Computing roots of F took 1876ms
Building F from its roots took 2316ms
Computing 1/F took 1048ms
Initializing table of differences for G took 116ms
Computing roots of G took 1640ms
Building G from its roots took 2380ms
Computing roots of G took 1844ms
Building G from its roots took 2340ms
Computing G * H took 692ms
Reducing G * H mod F took 912ms
Computing polyeval(F,G) took 4648ms
Computing product of all F(g_i) took 36ms
Step 2 took 19972ms
********** Factor found in step 2: 10880130373003275175614033001151500697
Found prime factor of 38 digits: 10880130373003275175614033001151500697
Composite cofactor ((17^509-1)/(2^4*1019*10181*27487*91621))/10880130373003275175614033001151500697 has 572 digits
[/CODE]

[QUOTE=YuL;565409]Thanks, I used to do that... Now I just run a GMP-ECM linked with GWNUM
and it does the job :)[/quote]Well now I'm jealous. Wish I knew how to compile things for Windows, let alone with fancy alternate libraries.

I'm not sure why it says this:[QUOTE=YuL;565409]Due to incompatible licenses, this binary file must not be distributed.[/QUOTE]Because the only info I can find for the license of GWNUM is this:[quote]Copyright (c) 1996-2017, Mersenne Research, Inc. All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:

(1) Redistributing source code must contain this copyright notice,
limitations, and disclaimer.
(2) If this software is used to find Mersenne Prime numbers, then
GIMPS will be considered the discoverer of any prime numbers found
and the prize rules at [url]http://mersenne.org/prize.htm[/url] will apply.[/quote]I don't know too much about licenses but it doesn't see like this would be incompatible with GPL to me.

This code exists in ECM, so presumably it CAN be GPL compliant?[CODE]#ifdef HAVE_GWNUM
#ifdef gwnum_is_gpl
if (! gwnum_is_gpl ())
#endif
printf ("Due to incompatible licenses, this binary file must not "
"be distributed.\n");[/CODE]

[QUOTE=lavalamp;565414]Well now I'm jealous. Wish I knew how to compile things for Windows, let alone with fancy alternate libraries.[/QUOTE]

Don't know a thing about compiling on Windows, but something like this worked for me on Linux. First get prime95 source and build gwnum:

[CODE]$ wget http://www.mersenne.org/ftp_root/gimps/p95v303b6.source.zip
$ unzip p95v303b6.source.zip
$ make -f make64 -j 16[/CODE]

After that, you should have a "gwnum.a". Then configure and build GMP-ECM with it:

[CODE]$ ./configure --with-gwnum=$HOME/p95/gwnum
$ make -j 16[/CODE]

The gcc command failed for me at first, so I manually had to redo it and add "-ldl" at the end.

[QUOTE=lavalamp;565414]Well now I'm jealous. Wish I knew how to compile things for Windows, let alone with fancy alternate libraries.

I'm not sure why it says this:Because the only info I can find for the license of GWNUM is this:I don't know too much about licenses but it doesn't see like this would be incompatible with GPL to me.

This code exists in ECM, so presumably it CAN be GPL compliant?[CODE]#ifdef HAVE_GWNUM
#ifdef gwnum_is_gpl
if (! gwnum_is_gpl ())
#endif
printf ("Due to incompatible licenses, this binary file must not "
"be distributed.\n");[/CODE][/QUOTE]

The easy answer on Windows 10 is usually to compile on WSL.

[QUOTE=henryzz;565441]The easy answer on Windows 10 is usually to compile on WSL.[/QUOTE]


Yes, I remember making it compile/work on Windows 10 back in early 2019
but I can't remember whether I did it using WSL or whether I was able to
make it compile using cygwin + mingw-gcc.

FWIW, updated list of factors found so far: [url]https://cs.stanford.edu/~rpropper/opn.txt[/url]

[QUOTE=ryanp;565661]FWIW, updated list of factors found so far: [url]https://cs.stanford.edu/~rpropper/opn.txt[/url][/QUOTE]

I get expired certificate.

Working fine yesterday and currently for me.

Chrome Canary 89.0.4349.2.
Windows 10, v2004.
Accessed from Germany.

[QUOTE=YuL;565270]Let n be a prime number with 500 < n < 1000.
I'm planning on doing some ECM on the numbers 17[SUP]n[/SUP]-1.
[...][/QUOTE]


Factors found so far:
[URL="http://factordb.com/index.php?id=1000000000048520533"]17 509[/URL] 10880130373003275175614033001151500697
[URL="http://factordb.com/index.php?id=1000000000048520545"]17 521[/URL] 507732028088571194591510571526693
[URL="http://factordb.com/index.php?id=1000000000048520547"]17 523[/URL] 89163041550752855557680359884199
[URL="http://factordb.com/index.php?id=1000000000048520565"]17 541[/URL] 210851698687146481442232546078496897
[URL="http://factordb.com/index.php?id=1000000000048520565"]17 541[/URL] 902304286550029874166103436203835437
[URL="http://factordb.com/index.php?id=1000000000048520935"]17 911[/URL] 1732550124080428168413011275808287
[URL="http://factordb.com/index.php?id=1000000000048520953"]17 929[/URL] 24635452104352854844270989359
[URL="http://factordb.com/index.php?id=1000000000048520991"]17 967[/URL] 34714203016693178317175265507286452661453
[URL="http://factordb.com/index.php?id=1000000000048521021"]17 997[/URL] 247157806053731011193258357444587433