Status of Search for Multifactorial Primes

For further information on  multifactorial primes please see Chris Caldwell's glossary page on Multifactorial Primes
This site continues the work of Ray Ballinger.

The MultiF project's, which started in 2003 aims at finding all primes of the form n!k+/-1 where 2<=k<=25

•  up to 10000*type for each n.  
•  a prime with at least 50000 digits for each n.

To participate

• email me, Ken Davis, at "kraDenken(at)yahoo(dot)com(dot)au" and reserve a type
• use multisieve to sieve a range of n (to eliminate those with small factors)
• use pfgw to find prps and prove primality
• Submit your prime to Chris Caldwell's The Prime Pages if big enough (Currently over 160000 digits) 
• Send me the Brillhart-Lehmer-Selfridge proof of primality output from pfgw
• I will add the (digits:nnnnn) and incorporate the data into the site

MultiF's position by number of Primes found
MultiF's position by score for Primes found

• 29/08/2010 Richard Kapek proves 142036!12+1 (digits: 55848), 148614!12+1 (digits: 58678), 237498!22+1 (digits: 53347), 238234!22-1 (digits: 53427), 253880!25+1 (digits: 50478), 254291!25+1 (digits: 50567), 256530!25+1 (digits: 51051), 257839!25+1 (digits: 51334) and 258852!25-1 (digits: 51554) prime

• 23/08/2010 Michael Lau proves 468661!23+1 (digits: 106707) and 470469!23+1(digits: 107152) prime

• 20/08/2010 Richard Kapek completes !19-1 to 220000, !21-1 to 280000, !24+1 to 300000 and proves 218492!19-1 (digits: 56410), 273983!21-1 (digits: 65282) and 282718!24+1 (digits: 59104)  prime

• 16/08/2010 Ken Davis proves 101129!9-1 (digits: 51361) prime

• 09/08/2010 Richard Kapek completes !21- to 250000, !24- to 300000, and proves 235416!21-1 (digits: 55355) and 296606!24-1 (digits: 62264) prime

• 03/08/2010 Richard Kapek completes !24+ to 260000, !14+ to 200000, !12- to 210000 and proves 177096!14+1 (digits: 60898) and 209898!12-1 (digits: 85497) prime

• 29/07/2010 Richard Kapek completes !12- to 200000, !24- to 260000, !24+ to 250000, proves 247674!24+1 (digits: 51185) prime and reserves !21-

• 26/07/2010 Richard Kapek completes !14+ to 170000

• 23/07/2010 Richard Kapek proves 156482!14+1 (digits: 53209) prime

• 22/07/2010 Richard Kapek completes !12-1 to 180000 & !14+1 to 150000  

Earlier news items

Recent changes are in Red

Type	nmaxtested	Digits*	Searcher	primes
n!2+1	100000	112762		primes
n!2-1	100000	93343		primes
n!3+1	100000	144697		primes
n!3-1	110000	84173	Andrea Pacini	primes
n!4+1	120000	58508	Don Routman	primes
n!4-1	120000	51252	Don Routman	primes
n!5+1	100000	69090		primes
n!5-1	100000	77730		primes
n!6+1	100000	75339		primes
n!6-1	100000	64524		primes
n!7+1	220000	203944	Rene Dohmen	primes
n!7-1	220000	131837	Rene Dohmen	primes
n!8+1	140760	61535	Kimmo Herranen	primes
n!8-1	100000	54736	Kimmo Herranen	primes
n!9+1	106000	46520	Ken Davis	primes
n!9-1	106000	51361	Ken Davis	primes
n!10+1	120000	50053		primes
n!10-1	120000	50001		primes
n!11+1	275259	124096	Ken Davis	primes
n!11-1	275259	125257	Ken Davis	primes
n!12+1	150000	58678		primes
n!12-1	210000	85497		primes
n!13+1	150000	52550		primes
n!13-1	150000	52097		primes
n!14+1	200000	60898		primes
n!14-1	200000	68950		primes
n!15+1	150000	43867	Richard Kapek	primes
n!15-1	150000	46186	Richard Kapek	primes
n!16+1	160000	43117	Richard Kapek	primes
n!16-1	160000	45370	Richard Kapek	primes
n!17+1	170000	46924	Richard Kapek	primes
n!17-1	170000	46817	Richard Kapek	primes
n!18+1	180000	46361	Richard Kapek	primes
n!18-1	180000	46900	Richard Kapek	primes
n!19+1	200000	50037		primes
n!19-1	220000	56410		primes
n!20+1	200000	73102	Masataka Oita (290700) 250001+	primes
n!20-1	200000	72521	Masataka Oita (288574) 250001+	primes
n!21+1	212048	49402	Masataka Oita (319773) ?	primes
n!21-1	280000	65282		primes
n!22+1	240000	53347		primes
n!22-1	240000	53527		primes
n!23+1	468698	107152	Michael Lau	primes
n!23-1	230000	49125	Matt Mills	primes
n!24+1	300000	59104		primes
n!24-1	300000	64262		primes
n!25+1	260000	51334		primes
n!25-1	260000	51554		primes
n!+/-1	30000+	+107707 -142891	Various	primes

* Number of digits in the largest known prime of this form

Multifactorial primes of a different flavour n!k+/-2