Contribution and Reservation

(26·10¹⁹¹-71)/9 =: 2(8)₁₉₀1_<192>; = 977 · [295689753212782895485044922097122711247583304901626293642670305925167747071534174911861708176958944615034686682588422608893437962015239394973274195382690776754236324348913908791083816672353_<189>] SUBMIT/RESERVE

Status

Expression:	(26·10¹⁹¹-71)/9
Composite Factor:	295689753212782895485044922097122711247583304901626293642670 305925167747071534174911861708176958944615034686682588422608 893437962015239394973274195382690776754236324348913908791083 816672353 (189-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 192.41-digit and the GNFS difficulty is 188.47-digit. SNFS must be faster than GNFS. It will take about 11 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 28881_191.
Put the following polynomial file 28881_191.poly in there too.
And then, run "perl factMsieve.pl 28881_191".

28881_191.poly ^*1

n: 295689753212782895485044922097122711247583304901626293642670305925167747071534174911861708176958944615034686682588422608893437962015239394973274195382690776754236324348913908791083816672353
m: 100000000000000000000000000000000000000
deg: 5
c5: 260
c0: -71
skew: 0.77
type: snfs
lss: 1
rlim: 11300000
alim: 11300000
lpbr: 28
lpba: 28
mfbr: 55
mfba: 55
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 189-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)

Level	B1	Reported runs Total / Required runs (Required runs for lower level)	Name
40	3e6	2336	Wataru Sakai	Sep 4, 2009
40	3e6	2336 / 2336
45	11e6	0 / 3962
45	11e6	/ 3962
50	43e6	0 / 7465 (1130)
50	43e6	/ 7465 (1130)
55	11e7	0 / 17751 (3097)
55	11e7	/ 17751 (3097)
60	26e7	0 / 42014 (7636)
60	26e7	/ 42014 (7636)

Command line to find prime factors up to about 45-digit

echo 295689753212782895485044922097122711247583304901626293642670305925167747071534174911861708176958944615034686682588422608893437962015239394973274195382690776754236324348913908791083816672353 | ecm -n -c 3962 11e6

Command line to find prime factors up to about 50-digit

echo 295689753212782895485044922097122711247583304901626293642670305925167747071534174911861708176958944615034686682588422608893437962015239394973274195382690776754236324348913908791083816672353 | ecm -n -c 7465 43e6

Command line to find prime factors up to about 55-digit

echo 295689753212782895485044922097122711247583304901626293642670305925167747071534174911861708176958944615034686682588422608893437962015239394973274195382690776754236324348913908791083816672353 | ecm -n -c 17751 11e7

Command line to find prime factors up to about 60-digit

echo 295689753212782895485044922097122711247583304901626293642670305925167747071534174911861708176958944615034686682588422608893437962015239394973274195382690776754236324348913908791083816672353 | ecm -n -c 42014 26e7

Submit factors

Make reservation

Back to Factorizations of near-repdigit numbers