Contribution and Reservation

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 190.51-digit and the GNFS difficulty is 124.86-digit. GNFS must be faster than SNFS. It will take about 4 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 43337_188.
2. Put the following polynomial file 43337_188.poly in there too.
3. And then, run "perl factMsieve.pl 43337_188".

# Murphy_E = 1.530948e-10, selected by Jeff Gilchrist
n: 72315988608969549766354716564088708863361398791668800127495140769387943021448338653197888223981621630401019958904218407786589
Y0: -1183090595104404290379437
Y1: 64847692273847
c0: -559051412188875961627115148480
c1: 10313471074653830483786056
c2: 2720906996349947309122
c3: -2661206114234297
c4: -13468462484
c5: 31200
skew: 232790.31
type: gnfs
# selected mechanically
rlim: 7100000
alim: 7100000
lpbr: 27
lpba: 27
mfbr: 52
mfba: 52
rlambda: 2.5
alambda: 2.5

*1 These parameters were not fully adjusted. The approximate expressions which were used for making the parameters are: d=log10(n); time=10^(d/21-4)[hours]; rlim=round(3*10^(d/37+3)); lpbr=floor(d/18+21); mfbr=floor(d/5+28); rlambda=floor(d/26+21)/10;

See also

• How to contribute your factors

The efforts by ECM to find small factors of this 125-digit composite number so far are as follows. According to the reports, unknown prime factors of this composite number are probably 35-digit or more. Please report your efforts by ECM. (Anonymous reports are not acceptable)