[QUOTE=Dubslow;312995]
I'll start on [URL="http://www.mersenneforum.org/showthread.php?p=311744#post311744"](5011^47-1)/(5011-1) C171[/URL].
[/QUOTE]
My first nice split from this group.
[code]PRP82 = 2748152743383198333631063110617899062221496876943804487243202957744764443992052933
PRP89 = 57222698680048096582853297361941384325957232430530113618095506002752879700317028009608129[/code]
I'll do the last one: [URL="http://www.mersenneforum.org/showthread.php?p=311744#post311744"](6143^47-1)/(6143-1) C175[/URL].

(2917^53-1)/(2917-1) is complete:

[CODE]prp48 factor: 292514328849269379764233793862686933016441854101
prp59 factor: 41239915441054802637475639195986364764183515245676000230801
prp75 factor: 124559917746120938256484860603410855985941501083630450790549589203743088921[/CODE]From the composites page:
1612999372481225633141261^7-1
[CODE]prp61 factor: 3465072145130790085667982781562995512349959524399559002177753
prp65 factor: 17577190192857809531247053539682002189089801934496932397816828227[/CODE]

[QUOTE=Dubslow;313128]
I'll do the last one: [URL="http://www.mersenneforum.org/showthread.php?p=311744#post311744"](6143^47-1)/(6143-1) C175[/URL].[/QUOTE]

[code]PRP97 = 4451712760042355381652858552380427360004864218669444818785516920141238358735202408981223001497981
PRP78 = 414044741688697488157621522554998391176080094609517319627535036050228699191253[/code]

From the composites page:

[URL="http://factordb.com/index.php?id=1100000000127606744"]822661829594479928946331604085883^5-1[/URL]
[code]PRP83 = 19669411552527732016690992535308839360104700598219739856203387000426858724103658441
PRP45 = 426240655270729408638031663874654915044370711
[/code]

(6269^53-1)/(6269-1) done:
[code]prp63 factor: 455985647105528276230007860903728825589536613233944008450587013
prp135 factor: 624350035746066666422804993887957566574296459648079205086500987963080365508050077609387476741620945849775396211051051319312844263743337[/code]

Already in factordb.

Chris

Thanks Dubslow, Mathew, RichD, jcrombie, and chris2be8. You have factored all eleven composites from [URL="http://www.mersenneforum.org/showthread.php?p=311744#post311744"]post 209[/URL]. These factors will help Pascal grow deeply nested factor chains.

For those interested in additional but less urgent work of this kind, please note that I keep the OPN [URL="http://oddperfect.org/composites.html"]composites page [/URL]stocked with C120 to C160 composites.

As expected, there are no more roadblocks of depth 6 in the proof tree for the lower bound of 10^1600. Thank you all for this ! As I see that such factorizations might improve people skills at SNFS, I will propose another list of interesting composites.

Thanks again,
Pascal

4742916019323619193044123^7-1 has factors:
prp56 factor: 22940938319267385949598533322784720121023025946494087789
prp63 factor: 696861063860122489341266605067361018639658127445897707875012673

Was there any improvement in poly over the obvious sextic I used? Halving the degree would have caused the opposite problem I think.

Just discovered the factors were already in the factordb. I should have checked but I got the number from a cached version of the page.

[QUOTE=henryzz;313703]Just discovered the factors were already in the factordb. I should have checked but I got the number from a cached version of the page.[/QUOTE]

Thank you. This is the first I have seen these factors - nobody had reported the factors nor told me they were going to factor this one. I checked all the composites on this page about two weeks ago, so it is a recent factorization. Long-dormant interest in these composites seems to have revived. To avoid duplication, I suggest emailing reservations to William at OddPerfect dot org.

William

yafu@home is factoring small composites in factordb. I think they are up to about 113 digits now. As are other people. I'm doing SNFS targets in that range. But I didn't do that one although I have done quite a few that look as if they came from Oddperfect.org.

I don't think William would want dozens of emails every day, not all relevant to him. And I havn't time to send them by hand and am not set up to send them automatically. I do post my results to factordb automatically so checking that should avoid wasted work.

Chris

[URL="http://factordb.com/index.php?id=1100000000423608342"](307189^31-1)/(307188)[/URL]
[code]***factors found***

PRP83 = 87807278564791893286253645174243635709626427499976357109471268919177366850083350479
PRP76 = 1423260777505600484936706794326359946141220621004149340031707016400600203423[/code]