Contribution and Reservation

(16·10²³⁸-7)/9 =: 1(7)₂₃₈_<239>; = 11953 · 128447281 · 1240954525497157_<16> · 4348652432785401065021_<22> · [2145680592866556409997535985694997319574732920214480357061247632916293854163181389588538081611667449347084182543255973640996940282189888119976966090966455971546853722398426695746834849557537_<190>] SUBMIT/RESERVE

Status

Expression:	(16·10²³⁸-7)/9
Composite Factor:	214568059286655640999753598569499731957473292021448035706124 763291629385416318138958853808161166744934708418254325597364 099694028218988811997696609096645597154685372239842669574683 4849557537 (190-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 240.60-digit and the GNFS difficulty is 189.33-digit. SNFS must be faster than GNFS. It will take about 436 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 17777_238.
Put the following polynomial file 17777_238.poly in there too.
And then, run "perl factMsieve.pl 17777_238".

17777_238.poly ^*1

n: 2145680592866556409997535985694997319574732920214480357061247632916293854163181389588538081611667449347084182543255973640996940282189888119976966090966455971546853722398426695746834849557537
m: 10000000000000000000000000000000000000000
deg: 6
c6: 4
c0: -175
skew: 1.88
type: snfs
lss: 1
rlim: 72000000
alim: 72000000
lpbr: 30
lpba: 30
mfbr: 61
mfba: 61
rlambda: 2.7
alambda: 2.7

*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 190-digit composite number so far are as follows. According to the reports, unknown prime factors of this composite number are probably 45-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
45	11e6	4500	Dmitry Domanov	Sep 2, 2009
45	11e6	4500 / 3853
50	43e6	0 / 6439
50	43e6	/ 6439
55	11e7	0 / 17466 (2671)
55	11e7	/ 17466 (2671)
60	26e7	0 / 41942 (7513)
60	26e7	/ 41942 (7513)
65	85e7	0 / 69396 (13587)
65	85e7	/ 69396 (13587)

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

echo 2145680592866556409997535985694997319574732920214480357061247632916293854163181389588538081611667449347084182543255973640996940282189888119976966090966455971546853722398426695746834849557537 | ecm -n -c 6439 43e6

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

echo 2145680592866556409997535985694997319574732920214480357061247632916293854163181389588538081611667449347084182543255973640996940282189888119976966090966455971546853722398426695746834849557537 | ecm -n -c 17466 11e7

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

echo 2145680592866556409997535985694997319574732920214480357061247632916293854163181389588538081611667449347084182543255973640996940282189888119976966090966455971546853722398426695746834849557537 | ecm -n -c 41942 26e7

Command line to find prime factors up to about 65-digit

echo 2145680592866556409997535985694997319574732920214480357061247632916293854163181389588538081611667449347084182543255973640996940282189888119976966090966455971546853722398426695746834849557537 | ecm -n -c 69396 85e7

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