A few months ago I decided that since finding a Mersenne prime is
extremely unlikely, and I don't have a good chance of finding any huge
prime, looking for factors of small unfactored Mersenne might be more
rewarding.
I didn't really expect to see anything so soon, but this evening the
following showed up:
ECM found a factor in curve #692, stage #1
Sigma=6367806696755784, B1=300, B2=3.
UID: gsnyder/P4-1.8GHz, M2161 has a factor:
117194366114889271070074059667667222873
If you like your numbers with commas, the 39-digit factor is
117,194,366,114,889,271,070,074,059,667,667,222,873
Below is the prime, and confirmation that the stated number is a factor
2^2161-1
33559897820263818973328366672316900265106281616071323131740682958447\
23020031958525072257855411838339438755855397849883223173639723336826\
11818963633898026623796104377359695298969744747862271248381904782724\
01410540964741344128534170717980528805095132859691435473682974821527\
66967600674003723458926658836927870073420383036522947349982262463351\
94612046602490095977412175612268046379624188025365954888124792184015\
0980840268026980669463410872194064753598131809670121757594834487\
38769988427120579195343840353631293116733882263414527206998792512969\
24724690039255472123968177736567130060069578721022002761288047769658\
671765880606929736241866036307612925951
(2^2161-1)%117194366114889271070074059667667222873
0
M2161 was number 10 on the list of smallest Mersenne numbers with no
known factor.
I am happy!!
Gerry (the lucky)
--
mailto:[EMAIL PROTECTED]
_
Unsubscribe list info -- http://www.ndatech.com/mersenne/signup.htm
Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
