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.

NFS

Use GGNFS and/or Msieve if GMP-ECM cannot find a factor. The SNFS difficulty of this composite number is 180.74-digit and the GNFS difficulty is 124.70-digit. GNFS must be faster than SNFS. It will take about 4 CPU-days to factor this composite number on 64-bit Opteron-2600MHz.

Steps of GNFS

1. Put factMsieve.pl to which $GGNFS_BIN_PATH and $NUM_CPUS were modified properly in the working directory 61111_179.
2. Put the following polynomial file 61111_179.poly in there too.
3. And then, run "perl factMsieve.pl 61111_179".

# Murphy_E = 1.511136e-10, selected by Jeff Gilchrist
n: 49872749867154635849498114267428018156814293490498079556170309821649579977580220644939911309877042053396719752191315137937549
Y0: -1262649721005303179818433
Y1: 40014062364289
c0: 43183058930049140574416809411680
c1: 878512329756059772155302064
c2: 1595054720124349656554
c3: -16409682066558075
c4: -2410289638
c5: 15540
skew: 437630.99
type: gnfs
# selected mechanically
rlim: 7000000
alim: 7000000
lpbr: 27
lpba: 27
mfbr: 52
mfba: 52
rlambda: 2.5
alambda: 2.5

These parameters were not fully adjusted. The approximate expressions which were used for making the parameters are: d=log10(n); time=5*10^(d/20-5)[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 40-digit or more. Please report your efforts by ECM. (Anonymous reports are not acceptable)