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 5970 c261 2,1183- T.Kleinjung 5811 C280 2,941- mersenneforum+NFS@Home+Dodson+Womack General number field sieve by size of number factored: 5852 C192 2,1175- J.Bos+T.Kleinjung 5723 C182 2,1157- J.Bos+T.Kleinjung Elliptic curve method: 5858 P73 2,1181- J.Bos+T.Kleinjung+A.K.Lenstra+P.Montgomery 5888 P73 2,1163- J.Bos+T.Kleinjung+A.K.Lenstra+P.Montgomery 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 December 22, 2010 2,929- c214 2,947- c217 2,991- c264 2,1007- c254 2,1009- c204 2,947+ c212 2,961+ c221 2,979+ c255 2,983+ c236 2,989+ c249 2,1814M c234 2,1822L c197 2,1822M c215 2,1838L c258 2,1846L c196 2,932+ c200 2,956+ c187 2,964+ c198 2,988+ c212 2,1000+ c217 3,569- c231 3,589- c213 3,593- c214 3,611- c222 3,613- c285 3,589+ c212 3,592+ c220 3,596+ c243 3,599+ c269 3,604+ c248 5,389- c231 5,397- c258 5,419- c224 5,431- c266 5,439- c244 5,386+ c223 5,394+ c265 5,397+ c270 5,401+ c236 5,409+ c271 6,349- c209 6,373- c287 6,377- c249 6,383- c264 6,391- c274 6,347+ c196 6,359+ c234 6,361+ c213 6,362+ c241 6,374+ c214 7,323- c241 7,337- c213 7,353- c263 7,359- c277 7,361- c290 7,323+ c229 7,326+ c258 7,331+ c253 7,332+ c199 7,334+ c205 10,277- c224 10,281- c210 10,283- c211 10,293- c218 10,323- c271 10,274+ c253 10,277+ c259 10,281+ c242 10,284+ c200 10,289+ c217 11,263- c209 11,269- c233 11,271- c221 11,281- c210 11,283- c268 11,263+ c252 11,269+ c202 11,271+ c267 11,272+ c201 11,278+ c211 12,257- c218 12,269- c205 12,271- c234 12,277- c285 12,281- c294 12,271+ c250 12,274+ c213 12,283+ c194 12,284+ c252 12,289+ c265