Reserving C235_129_67 for factoring by SNFS.

http://www.mersenneforum.org/showthread.php?t=19368
 

Taking C171_121_105 for GNFS

C166_117_76
 

C166_117_76 factored by Ryan using GNFS.

[code]
p66 = 983482363005195461050945392668453786790198935996929033893296326313
p100 = 3131359607817460805491762734094660520460885356395630349963727421583098178415289140562492568546120777
[/code]

C171_144_82
 

Factored by Ryan using SNFS.

[url=http://factordb.com/index.php?id=1000000000044701168]p80*p92[/url]

Ryan factored two more via SNFS

C195_143_37
[url=http://factordb.com/index.php?id=1000000000044656167]p69*p127[/url]

C184_148_72
[url=http://factordb.com/index.php?id=1000000000044691172]p83*p102[/url]

[QUOTE=swellman;404823]At last word, Ryan was attempting this septic. Sieving appeared to flow quite nicely - very pretty indeed!

Sean[/QUOTE]

Ryan succeeded in building a matrix for this factorization. ETA is 2291 hrs(!)

He is trying additional sieving to get a better matrix but worst case the job should finish in late September.

So I'm reserving this C300 for him?

Septic, nice!

Tell him that if he will have problems with sqrt phase, I may be able to debug.
If anything, it should be better than a couple octics that I ran (a certain stage's complexity is ~p^d where p is a small prime and d is the degree, so unlike sextics, p had to be lowered from 59 to 17 and I even tried as low as 7, or else the bruteforce routine never reaches the solution because 59^8 is too large a space to explore). The smaller the p, the more sqrt attempts will fail to converge however. For a septic, he may want to use 17, 19 or 23.

-xyyxf: yes, please reserve this composite for Ryan. Also he is still tackling C282_140_137, with a sextic.

-Batalov: I will pass on your advice to Ryan. Thanks!

[QUOTE=XYYXF;404533]C282_140_137 has SNFS difficulty close to 300 and quite large coefficients. A lot of ECM is needed before sieving.

Why that one? I'd choose something like C292_139_132 instead.

BTW, C300_141_133 survived a lot of ECM and has a pretty septic: 133*(133[sup]20[/sup])[sup]7[/sup] + (141[sup]19[/sup])[sup]7[/sup] = 2 * C300[/QUOTE]

I poked around a bit, and found a few other candidates with seemingly nice septics:

C310_147_142
C311_148_133
C303_150_119

And an octic

C300_145_136

Thoughts? I have not test sieved these. On my hardware, that's like picking the fastest molasses in wintertime.

Any other potential septics/optics for the 14 or bust that I might have missed? Or even sextics? I realize this is just a thought experiment at this time, but it is interesting and educational (for me anyway).

Thanks.

Actually, The Law of Reruns applies here:
If you have watched a TV series only once, and you watch it again, it will be a rerun of the same episode. :rolleyes:
With octics and septics, it is exactly the same. I've heard a similar saying about Mt.Fuji:
"A wise man climbs Fuji once, and a fool twice," but the true wisdom of this phrase is usually only learned the hard way, the Japanese say.

In other words, I would do (almost) all of them with sextics (except GNFS's).

[COLOR="Blue"]...Or maybe not!
Played with the Ryan's (most likely) septic against sextics: it seems to make sense, even if it was hard to believe at first.[/COLOR]