fond of a factor? Urn yourself to become inane - Page 5

ckdo · 2011-01-07, 06:57

M39512171 has a factor: 23887910757239756825399

k = 2039*71597*2070643

ckdo · 2011-01-10, 18:49

M90012887 has a factor: 439952565941844992833877634700202506740401

k1 = 3*3*5*7*11*19*52177399
k2 = 5*11*71851282747

KingKurly · 2011-01-10, 19:14

Quote:

Originally Posted by ckdo

M90012887 has a factor: 439952565941844992833877634700202506740401

k1 = 3*3*5*7*11*19*52177399
k2 = 5*11*71851282747

Goodness, that's a large factor. P-1, I presume?

ckdo · 2011-01-10, 19:53

Quote:

Originally Posted by KingKurly

Goodness, that's a large factor. P-1, I presume?

TF. First dual 70 bit factors I've seen for an exponent.

lorgix · 2011-01-12, 17:22

Quote:

Originally Posted by ckdo

TF. First dual 70 bit factors I've seen for an exponent.

I didn't know that was possible.

Mini-Geek · 2011-01-12, 17:53

Quote:

Originally Posted by lorgix

I didn't know that was possible.

Why not? There's no reason a number can't have two factors that happen to have the same bit length. There's probably about a 1/4900 (70^(-2)) chance that any particular Mersenne number has two factors that are 70 bits long, so it should be rare, but it's possible.

lorgix · 2011-01-12, 18:27

Quote:

Originally Posted by Mini-Geek

Why not? There's no reason a number can't have two factors that happen to have the same bit length. There's probably about a 1/4900 (70^(-2)) chance that any particular Mersenne number has two factors that are 70 bits long, so it should be rare, but it's possible.

I thought it would stop after finding the smaller one.

I wouldn't have been surprised to see a composite factor found by P-1.

axn · 2011-01-12, 18:43

Quote:

Originally Posted by Mini-Geek

Why not? There's no reason a number can't have two factors that happen to have the same bit length. There's probably about a 1/4900 (70^(-2)) chance that any particular Mersenne number has two factors that are 70 bits long, so it should be rare, but it's possible.

Because prime95 will stop at the first found factor?!

ET_ · 2011-01-12, 19:41

Quote:

Originally Posted by axn

Because prime95 will stop at the first found factor?!

Not anymore, IIRC

Luigi

lorgix · 2011-01-12, 19:59

Why multiply them, instead of reporting them as they are found?

axn · 2011-01-12, 20:48

Quote:

Originally Posted by ET_

Not anymore, IIRC

Luigi

Huh? It used to be that, once upon a time, p95 used to go ahead with TF even if a factor was found, just to make sure that no _smaller_ factor was missed. Then, that was removed. You mean to say that this (mis)feature has been reintroduced?!

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2011-01-07, 06:57	#45
ckdo Dec 2007 Cleves, Germany 2·5·53 Posts	M39512171 has a factor: 23887910757239756825399 k = 2039715972070643

2011-01-10, 18:49	#46
ckdo Dec 2007 Cleves, Germany 2×5×53 Posts	M90012887 has a factor: 439952565941844992833877634700202506740401 k1 = 3357111952177399 k2 = 51171851282747

2011-01-12, 19:59	#54
lorgix Sep 2010 Scandinavia 3·5·41 Posts	Why multiply them, instead of reporting them as they are found?