Contribution and Reservation

(79·10¹⁹⁷-7)/9 =: 8(7)₁₉₇_<198>; = 29 · 15823 · 7609075226947_<13> · [251400350075079437268822700859414979079521765999642570817705964277890819431167074626658279760132912426773247616716424313280022251401463371065378047506832691756001923318212529262873_<180>] SUBMIT/RESERVE

Status

Expression:	(79·10¹⁹⁷-7)/9
Composite Factor:	251400350075079437268822700859414979079521765999642570817705 964277890819431167074626658279760132912426773247616716424313 280022251401463371065378047506832691756001923318212529262873 (180-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.

SNFS

Use GGNFS and/or Msieve if GMP-ECM cannot find a factor. The SNFS difficulty of this composite number is 200.99-digit and the GNFS difficulty is 179.40-digit. SNFS must be faster than GNFS. It will take about 21 CPU-days to factor this composite number on 64-bit Opteron-2600MHz.

Put factMsieve.pl to which $GGNFS_BIN_PATH and $NUM_CPUS were modified properly in the working directory 87777_197.
Put the following polynomial file 87777_197.poly in there too.
And then, run "perl factMsieve.pl 87777_197".

87777_197.poly ^*1

n: 251400350075079437268822700859414979079521765999642570817705964277890819431167074626658279760132912426773247616716424313280022251401463371065378047506832691756001923318212529262873
m: 5000000000000000000000000000000000000000
deg: 5
c5: 316
c0: -875
skew: 1.23
type: snfs
lss: 1
rlim: 15700000
alim: 15700000
lpbr: 29
lpba: 29
mfbr: 56
mfba: 56
rlambda: 2.6
alambda: 2.6

*1 These parameters were not fully adjusted. The approximate expressions which were used for making the parameters are: deg=expt<=105?4:expt<=210?5:6 or expt<=144?4:6; d=log10(c[deg])+deg*log10(m)[digits]; time=10^(d/30-4)[hours]; skew=|c0/c[deg]|^(1/deg); rlim=round(7*10^(d/60+3)); lpbr=floor(d/25+21); mfbr=floor(d/8+31); rlambda=floor(d/25+18)/10;

Efforts by ECM

The efforts by ECM to find small factors of this 180-digit composite number are not reported yet. Please report your efforts by ECM. (Anonymous reports are not acceptable)

Level	B1	Reported runs Total / Required runs (Required runs for lower level)
20	11e3	0 / 74
20	11e3	/ 74
25	5e4	0 / 214 (21)
25	5e4	/ 214 (21)
30	25e4	0 / 430 (50)
30	25e4	/ 430 (50)
35	1e6	0 / 904 (118)
35	1e6	/ 904 (118)
40	3e6	0 / 2350 (322)
40	3e6	/ 2350 (322)

Command line to find prime factors up to about 20-digit

echo 251400350075079437268822700859414979079521765999642570817705964277890819431167074626658279760132912426773247616716424313280022251401463371065378047506832691756001923318212529262873 | ecm -n -c 74 11e3

Command line to find prime factors up to about 25-digit

echo 251400350075079437268822700859414979079521765999642570817705964277890819431167074626658279760132912426773247616716424313280022251401463371065378047506832691756001923318212529262873 | ecm -n -c 214 5e4

Command line to find prime factors up to about 30-digit

echo 251400350075079437268822700859414979079521765999642570817705964277890819431167074626658279760132912426773247616716424313280022251401463371065378047506832691756001923318212529262873 | ecm -n -c 430 25e4

Command line to find prime factors up to about 35-digit

echo 251400350075079437268822700859414979079521765999642570817705964277890819431167074626658279760132912426773247616716424313280022251401463371065378047506832691756001923318212529262873 | ecm -n -c 904 1e6

Command line to find prime factors up to about 40-digit

echo 251400350075079437268822700859414979079521765999642570817705964277890819431167074626658279760132912426773247616716424313280022251401463371065378047506832691756001923318212529262873 | ecm -n -c 2350 3e6

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