Factoring humongous Cunningham numbers

[R.D. Silverman]

Originally Posted by jyb

User Favebook on Yoyo@home has found a 77-digit prime factor of 6+5,395 by ECM, with a B1 of 260,000,000. This is the 4th largest prime factor ever found by ECM.

Kudos. Very nice indeed.

The reservations page is still down. Is anyone keeping track?

[kruoli]

For finished jobs, jyb already promised that posting them in the NFS@home post-processing threads is sufficient.

[jyb]

Originally Posted by kruoli

For finished jobs, jyb already promised that posting them in the NFS@home post-processing threads is sufficient.

Well yes, it's sufficient for me to pick them up and add them to the records of HCN factors found. But 1) that wouldn't be an appropriate place to post information about factors found by someone other than NFS@Home, and 2) I don't think that's what Bob was asking about.

I think what Bob meant was whether anyone was tracking reservations. The answer is yes, but not in a public way at the moment. For quite a long time before the reservation page went down, the only reservations were for NFS@Home anyway. And anybody can see what NFS@Home is doing, either via this forum or on its own site. But if anybody else wishes to reserve a number for their own factoring attempt, they can certainly let me know, but that's of limited utility, since that information wouldn't be public. When I get a chance I will add a "Who's factoring what now" page to my site, similar to what Sam has for Cunningham numbers, at least until we can get a better reservation page back up and running.

[jyb]

I've just updated the tables again, incorporating all factors known to me by the end of June 21 (GMT). Please let me know if you see any errors or omissions. There were 27 new factors found since the last update, of which 24 completed the factorization of their respective numbers. There are now 500 composites remaining in the tables. The smallest composite has 197 digits. SNFS difficulties start at 243 for quartic polynomials, and the minimum difficulty for non-quartic polynomials has risen to 271.

Most factors were found with NFS, all by NFS@Home and an array of volunteer post-processors. The remaining factors were found by Yoyo@home, using ECM. One of them was a 77-digit factor, the fourth largest ever found by ECM.

Here are the factors found since the last update, showing appropriate credit:

12-7	945M	C197	2661816643001929058587283981689696811490701222452019595469920516676879023191221991423732551.	P107		NFS@Home & G Childers	GNFS	2023-04-29
10+3	269	C236	302456458270923328278805649516604837209528377677546178506522847567775268529.	P161				NFS@Home & G Childers	SNFS	2023-05-03
4+3	1347M	C266	9883282683678180393404616264813709645348004978625770206116714142171.	P199					NFS@Home & G Childers	SNFS	2023-05-03
10+9	269	C243	53591548055334072590878531980802408945180104831346701302549054648138785581525339146668884049328690942299.	P139	NFS@Home & G Childers	SNFS	2023-05-05
3+2	611	C215	1726758161481354769457854440659286098933003979655132788586249.	C155						NFS@Home & O Kruse	SNFS	2023-05-09
3+2	611	C155	1096821015553705097014157549956050057057069695189948586938845800822572911.	P82				NFS@Home & O Kruse	SNFS	2023-05-09
7+2	742M	C217	7465993799813407169953973359800286416114115778069333857778119238847589636279410077.	P136			NFS@Home & S Wellman	SNFS	2023-05-10
11+3	295	C229	88533179339838412342355534391164305303423045895021862506831.	C170						Yoyo@home		ECM	2023-05-11
6+5	395	C202	79632490363499039771085988101713956873090985066875428007643233693630470417031.	P125				Yoyo@home		ECM	2023-05-12
11+2	289	C195	133642006508847390011650141652241530546995622027523581355560398380321922785000816755737.	P109		NFS@Home & M Vang	GNFS	2023-05-14
5-4	935L	C210	20567872983872082932550969066444450799669782132821378202571.	P152						Yoyo@home		ECM	2023-05-16
3+2	566	C216	678692116947350456933193053493391555033136586543567597219184723318128383637985163385485410237783125901.	P114	NFS@Home & O Kruse	SNFS	2023-05-17
10+3	1110L	C200	15436713650454173198214271665460174292557902632822940325321.	P142						Yoyo@home		ECM	2023-05-18
4+3	449	C216	1527544089331734903940993461872396687659793894369816225935712229751.	P150					NFS@Home & O Kruse	SNFS	2023-05-22
9-2	283	C237	11054477736353310542950757696117507643400166180991325970232282644181936859406927.	P158			NFS@Home & O Kruse	SNFS	2023-05-25
7-3	1113M	C249	24927771712308924833085245982933999569438064925628444475853747803792354587392847487057556645824487.	P151	NFS@Home & S Wellman	SNFS	2023-05-28
4-3	449	C267	79822941257886573815840672852875529811420112843062098219880076584321109302172733754506841324351254801058086436650405349368689.	P142	NFS@Home & O Kruse	SNFS	2023-05-31
12-7	251	C234	102745936536572307958039001017264921535761186455294568090451992642338779436724847.	P154			NFS@Home & O Kruse	SNFS	2023-06-02
9-5	635L	C208	49361290688033119330343217265999179787573620136861630847711551.	P146						NFS@Home & M Vang	SNFS	2023-06-03
6+5	346	C255	45061980269776637716161741292558723125959989399378276693070043759417205253356518995697773368934147621401.	P151	NFS@Home & S Wellman	SNFS	2023-06-04
9+8	284	C263	285885178182539985255525986767531035293039442743373356798844537750423768327698359459314326476983813287064241.	P155	NFS@Home & O Kruse	SNFS	2023-06-09
11+3	295	C170	153404406163660647731735303648540738104149719695385121940696533172901.	P101					NFS@Home & O Kruse	GNFS	2023-06-09
10+7	268	C264	97378591920288934640979556379778037627572594719933425543680219854209396980001609969718449.	P175		NFS@Home & G Childers	SNFS	2023-06-10
7-2	323	C222	11821817485620025855856632703474095219408204974516476790233.	P164						Yoyo@home		ECM	2023-06-13
12+7	251	C265	27272796856815757146538809156837846545666253170339590372777366628382625626721.	C189				NFS@Home & G Childers	SNFS	2023-06-16
12+7	251	C189	87621417871238682640842098498152051530393590358447521132495252643511325497605249794743.	P103			NFS@Home & G Childers	SNFS	2023-06-16
4+3	1353M	C200	199217073338921040265749251736309823873891561316841721386645793028929523373451.	P122				NFS@Home & G Childers	SNFS	2023-06-21