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 178.60-digit and the GNFS difficulty is 124.14-digit. GNFS may 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 33337_178.
2. Put the following polynomial file 33337_178.poly in there too.
3. And then, run "perl factMsieve.pl 33337_178".

# Murphy_E = 1.601051e-10, selected by Jeff Gilchrist
n: 13721803576811817885681690766567074498750646980891844789336195718859769978139856006456462401531345020909342029534402999813881
Y0: -864366673703682846747469
Y1: 43151535520363
c0: -953316009339433733021136033024
c1: 18034484302872112056517056
c2: 202171704467223768852
c3: -3597978062516861
c4: -11101937798
c5: 28440
skew: 156329.76
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)