Contribution and Reservation

(5·10¹⁸⁷-23)/9 =: (5)₁₈₆3_<187>; = 3 · 1249569676018218532056891295863517_<34> · [1481991670726852801036337564124989580909663768841067210637083024250974479404992726846367777814579781927851301822010278319654383652691909116064846052888903_<154>] (matsui / GMP-ECM 6.0 B1=4194304, sigma=890821030 for P34 / Nov 25, 2007) SUBMIT/RESERVE

Status

Expression:	(5·10¹⁸⁷-23)/9
Composite Factor:	148199167072685280103633756412498958090966376884106721063708 302425097447940499272684636777781457978192785130182201027831 9654383652691909116064846052888903 (154-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 188.60-digit and the GNFS difficulty is 153.17-digit. SNFS must be faster than GNFS. It will take about 8 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 55553_187.
Put the following polynomial file 55553_187.poly in there too.
And then, run "perl factMsieve.pl 55553_187".

55553_187.poly ^*1

n: 1481991670726852801036337564124989580909663768841067210637083024250974479404992726846367777814579781927851301822010278319654383652691909116064846052888903
m: 20000000000000000000000000000000000000
deg: 5
c5: 125
c0: -184
skew: 1.08
type: snfs
lss: 1
rlim: 9700000
alim: 9700000
lpbr: 28
lpba: 28
mfbr: 54
mfba: 54
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 154-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 1481991670726852801036337564124989580909663768841067210637083024250974479404992726846367777814579781927851301822010278319654383652691909116064846052888903 | ecm -n -c 74 11e3

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

echo 1481991670726852801036337564124989580909663768841067210637083024250974479404992726846367777814579781927851301822010278319654383652691909116064846052888903 | ecm -n -c 214 5e4

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

echo 1481991670726852801036337564124989580909663768841067210637083024250974479404992726846367777814579781927851301822010278319654383652691909116064846052888903 | ecm -n -c 430 25e4

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

echo 1481991670726852801036337564124989580909663768841067210637083024250974479404992726846367777814579781927851301822010278319654383652691909116064846052888903 | ecm -n -c 904 1e6

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

echo 1481991670726852801036337564124989580909663768841067210637083024250974479404992726846367777814579781927851301822010278319654383652691909116064846052888903 | ecm -n -c 2350 3e6

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