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: 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 April 25, 2010 2,919- c261 2,929- c214 2,937- C212 2,947- c217 2,953- c215 2,881+ c190 2,947+ c212 2,955+ c214 2,961+ c221 2,979+ c255 2,1766L c258 2,1774M c216 2,1798L c207 2,1814M c234 2,1822L c197 2,904+ c210 2,932+ c200 2,956+ c187 2,964+ c198 2,988+ c212 3,563- c199 3,569- c231 3,589- c213 3,593- c214 3,562+ c255 3,563+ c239 3,568+ c268 3,581+ c197 3,583+ c225 5,389- c231 5,397- c258 5,409- c282 5,419- c224 5,427- c205 5,386+ c223 5,394+ c265 5,397+ c270 5,400+ c205 5,401+ c236 6,349- c209 6,365- c185 6,373- c287 6,377- c249 6,383- c264 6,346+ c241 6,347+ c196 6,353+ c178 6,359+ c234 6,361+ c213 7,323- c241 7,335- c219 7,337- c213 7,353- c263 7,359- c277 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 10,272+ c212 10,274+ c253 10,277+ c259 10,281+ c242 10,284+ c200 11,263- c209 11,269- c233 11,271- c275 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 12,254+ c230 12,265+ c185 12,271+ c250 12,274+ c213 12,283+ c194