List of recent champions for factoring Cunningham numbers: Special number field sieve by size of number factored: 5501 c307 2,1039- K.Aoki+J.Franke+T.Kleinjung+A.K.Lenstra+D.A.Osvik 5811 C280 2,941- mersenneforum+NFS@Home+Dodson+Womack Special number field sieve by SNFS difficulty: 5501 c307 2,1039- K.Aoki+J.Franke+T.Kleinjung+A.K.Lenstra+D.A.Osvik 5811 C280 2,941- mersenneforum+NFS@Home+Dodson+Womack General number field sieve by size of number factored: 5723 C182 2,1157- J.Bos+T.Kleinjung 5667 C180 5,421- Mersenneforum+Womack Elliptic curve method: 5418 P67 10,381+ B. Dodson ECMNET 5135 P66 3,466+ B. Dodson ECMNET Largest penultimate prime factor (ultimate factor shown also): 5714 p128*p140 5,383+ Childers/Dodson 5654 p127*p136 6,392+ Childers/Dodson First five holes in each table on February 4, 2010 2,887- c210 2,899- c185 2,913- c233 2,919- c261 2,929- c214 2,881+ c190 2,887+ c207 2,913+ c232 2,947+ c212 2,955+ c214 2,1706M c244 2,1714L c191 2,1718L c233 2,1718M c200 2,1754M c180 2,904+ c210 2,932+ c200 2,956+ c187 2,964+ c198 2,980+ c162 3,563- c199 3,569- c231 3,589- c213 3,593- c214 3,559+ c225 3,562+ c255 3,563+ c239 3,568+ c268 3,575+ c196 5,383- c183 5,389- c231 5,391- c161 5,397- c258 5,409- c282 5,377+ c171 5,382+ c172 5,386+ c223 5,394+ c265 5,397+ c270 6,349- c209 6,355- c206 6,365- c185 6,371- c217 6,373- c287 6,344+ c190 6,346+ c241 6,347+ c196 6,353+ c178 6,355+ c211 7,323- c241 7,335- c219 7,337- c213 7,353- c263 7,359- c277 7,314+ c215 7,323+ c229 7,326+ c258 7,331+ c253 7,332+ c199 10,271- c214 10,277- c224 10,281- c210 10,283- c211 10,293- c218 10,272+ c212 10,274+ c253 10,275+ c188 10,277+ c259 10,278+ c162 11,257- c226 11,263- c209 11,265- c202 11,269- c233 11,271- c275 11,254+ c228 11,263+ c252 11,269+ c202 11,271+ c267 11,272+ c201 12,257- c218 12,269- c205 12,271- c234 12,277- c285 12,281- c294 12,254+ c230 12,265+ c185 12,266+ c179 12,271+ c250 12,274+ c213