Contribution and Reservation

(19·10¹⁷⁶-1)/9 =: 2(1)₁₇₆_<177>; = 157 · 448993 · 939193 · [3188724670729496744959060639098552022684820818843964422759175014924236554302734391035293579472988398720143227361134707737362991149311171107348415358179597769834027_<163>] SUBMIT/RESERVE

Status

Expression:	(19·10¹⁷⁶-1)/9
Composite Factor:	318872467072949674495906063909855202268482081884396442275917 501492423655430273439103529357947298839872014322736113470773 7362991149311171107348415358179597769834027 (163-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 178.48-digit and the GNFS difficulty is 162.50-digit. SNFS must be faster than GNFS. It will take about 4 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 21111_176.
Put the following polynomial file 21111_176.poly in there too.
And then, run "perl factMsieve.pl 21111_176".

21111_176.poly ^*1

n: 3188724670729496744959060639098552022684820818843964422759175014924236554302734391035293579472988398720143227361134707737362991149311171107348415358179597769834027
m: 200000000000000000000000000000000000
deg: 5
c5: 95
c0: -16
skew: 0.70
type: snfs
lss: 1
rlim: 6600000
alim: 6600000
lpbr: 28
lpba: 28
mfbr: 53
mfba: 53
rlambda: 2.5
alambda: 2.5

*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 163-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 3188724670729496744959060639098552022684820818843964422759175014924236554302734391035293579472988398720143227361134707737362991149311171107348415358179597769834027 | ecm -n -c 74 11e3

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

echo 3188724670729496744959060639098552022684820818843964422759175014924236554302734391035293579472988398720143227361134707737362991149311171107348415358179597769834027 | ecm -n -c 214 5e4

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

echo 3188724670729496744959060639098552022684820818843964422759175014924236554302734391035293579472988398720143227361134707737362991149311171107348415358179597769834027 | ecm -n -c 430 25e4

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

echo 3188724670729496744959060639098552022684820818843964422759175014924236554302734391035293579472988398720143227361134707737362991149311171107348415358179597769834027 | ecm -n -c 904 1e6

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

echo 3188724670729496744959060639098552022684820818843964422759175014924236554302734391035293579472988398720143227361134707737362991149311171107348415358179597769834027 | ecm -n -c 2350 3e6

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