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 6064 C299 2,1031- NFS@Home Special number field sieve by SNFS difficulty: 5501 C307 2,1039- K.Aoki+J.Franke+T.Kleinjung+A.K.Lenstra+D.A.Osvik 6064 C299 2,1031- NFS@Home General number field sieve by size of number factored: 6084 C197 7,374+ mersenneforum+Dodson+Womack 6054 C197 2,1196+ 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 March 23, 2011 2,929- c214 2,947- c217 2,991- c264 2,1007- c254 2,1009- c204 2,947+ c212 2,961+ c221 2,983+ c236 2,989+ c249 2,991+ c224 2,1846L c196 2,1874L c195 2,1894M c227 2,1898L c219 2,1898M c257 2,1000+ c217 2,1028+ c241 2,1052+ c300 2,1072+ c271 2,1076+ c238 3,589- c213 3,593- c214 3,613- c285 3,617- c277 3,619- c207 3,589+ c212 3,592+ c220 3,596+ c243 3,599+ c269 3,604+ c248 5,419- c224 5,431- c266 5,449- c271 5,469- c210 5,473- c268 5,401+ c236 5,409+ c271 5,419+ c236 5,421+ c250 5,422+ c235 6,373- c287 6,383- c264 6,391- c274 6,401- c274 6,407- c241 6,359+ c234 6,361+ c213 6,362+ c241 6,376+ c224 6,389+ c242 7,337- c213 7,353- c263 7,359- c224 7,361- c290 7,365- c221 7,331+ c253 7,332+ c199 7,334+ c205 7,337+ c237 7,346+ c251 10,281- c210 10,283- c211 10,323- c271 10,337- c268 10,341- c226 10,281+ c242 10,284+ c200 10,289+ c217 10,292+ c258 10,298+ c267 11,269- c233 11,271- c221 11,283- c268 11,293- c300 11,299- c212 11,269+ c202 11,271+ c267 11,272+ c201 11,278+ c211 11,283+ c258 12,257- c218 12,269- c205 12,271- c234 12,277- c285 12,281- c235 12,271+ c250 12,274+ c213 12,283+ c194 12,284+ c252 12,289+ c265