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 190.30-digit and the GNFS difficulty is 124.19-digit. GNFS must be faster than SNFS. It will take about 3 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 13337_189.
2. Put the following polynomial file 13337_189.poly in there too.
3. And then, run "perl factMsieve.pl 13337_189".

# Murphy_E = 1.636908e-10, selected by Jeff Gilchrist
n: 15491522938381573906448297533275873383308834950095077807151223147290939991688951864017987014415449626456465487307308089469119
Y0: -1004067236851368097376921
Y1: 26777904002947
c0: 3323217375526080327072445802880
c1: 556268730508422960969096
c2: -523268751061528227138
c3: -2712484193430191
c4: 10960026368
c5: 15180
skew: 245124.25
type: gnfs
# selected mechanically
rlim: 6800000
alim: 6800000
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)