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(38·10204+61)/9 =
4(2)2039<205>
= 11 · 79 · 1709 · 791090537 · 1987580262395825291<19> · 703840872152480294886493557323<30> · [2568939641075105630577865457086241354362500166153495772886449023670458981353818933105040106819187594102872385338262568741217081681324872095989<142>] (Makoto Kamada / GMP-ECM 6.2.1 B1=25e4, sigma=707394649 for P30 / Dec 22, 2008) SUBMIT/RESERVE

Status

Expression:(38·10204+61)/9
Composite Factor:256893964107510563057786545708624135436250016615349577288644
902367045898135381893310504010681918759410287238533826256874
1217081681324872095989
(142-digit)
Status:Not factored. Not reserved. You can submit its factors or reserve it for submitting in the future.

How to factor it

ECM, P-1, P+1

Look for prime factors by GMP-ECM first. Refer to the section "Efforts by ECM". Not only ECM but also P-1/P+1 may be helpful.

GNFS

Use GGNFS and/or Msieve if GMP-ECM cannot find a factor. The SNFS difficulty of this composite number is 206.28-digit and the GNFS difficulty is 141.41-digit. GNFS must be faster than SNFS. It will take about 23 CPU-days to factor this composite number on 64-bit Opteron-2600MHz.

  1. Put factMsieve.pl to which $GGNFS_BIN_PATH and $NUM_CPUS were modified properly in the working directory 42229_204.
  2. Put the following composite number file 42229_204.n in there too.
  3. And then, run "perl factMsieve.pl 42229_204".
42229_204.n
n: 2568939641075105630577865457086241354362500166153495772886449023670458981353818933105040106819187594102872385338262568741217081681324872095989

See also


Efforts by ECM

The efforts by ECM to find small factors of this 142-digit composite number so far are as follows. According to the reports, unknown prime factors of this composite number are probably 40-digit or more. Please report your efforts by ECM. (Anonymous reports are not acceptable)

LevelB1Reported runs
Total / Required runs
(Required runs for lower level)		Name 
403e60 / 0  
4511e60 / 2725  
/ 2725
5043e6300Serge BatalovJan 5, 2009
200Serge BatalovJan 5, 2009
500 / 7553 (1277)  
/ 7053 (777)  
5511e70 / 17591 (2926)  
/ 17591 (2926)  
6026e70 / 41959 (7567)  
/ 41959 (7567)  
Command line to find prime factors up to about 45-digit
echo 2568939641075105630577865457086241354362500166153495772886449023670458981353818933105040106819187594102872385338262568741217081681324872095989 | ecm -n -c 2725 11e6
Command line to find prime factors up to about 50-digit
echo 2568939641075105630577865457086241354362500166153495772886449023670458981353818933105040106819187594102872385338262568741217081681324872095989 | ecm -n -c 7053 43e6
Command line to find prime factors up to about 55-digit
echo 2568939641075105630577865457086241354362500166153495772886449023670458981353818933105040106819187594102872385338262568741217081681324872095989 | ecm -n -c 17591 11e7
Command line to find prime factors up to about 60-digit
echo 2568939641075105630577865457086241354362500166153495772886449023670458981353818933105040106819187594102872385338262568741217081681324872095989 | ecm -n -c 41959 26e7

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