List of recent champions for factoring Cunningham numbers: Special number field sieve by size of number factored: 4949 c248 2,1642M Aoki+Kida+Shimoyama+Sonoda+Ueda/CRYPTREC 4757 C244 2,809- Franke/Kleinjung/Bahr/CWI Special number field sieve by SNFS difficulty: 4949 c248 2,1642M Aoki+Kida+Shimoyama+Sonoda+Ueda/CRYPTREC 4983 c239 2,811- NFSNET" General number field sieve by size of number factored: 5158 C176 11,281+ Aoki+Kida+Shimoyama+Ueda 4924 C164 2,1826L Aoki+Kida+Shimoyama+Sonoda+Ueda/CRYPTREC Elliptic curve method: 5135 P66 3,466+ B. Dodson ECMNET 5139 P62 2,2034L B. Dodson ECMNET Largest penultimate prime factor (ultimate factor shown also): 4835 p105*p107 10,223- Dodson/AKL/Leyland/CWI 5101 p102*p106 12,597M CWI First five holes in each table on June 24, 2005 2,739- c168 2,761- c189 2,781- c158 2,787- c204 2,793- c186 2,719+ c166 2,749+ c189 2,751+ c166 2,779+ c212 2,791+ c192 2,1322M c175 2,1334L c186 2,1342M c138 2,1346L c183 2,1366L c193 2,736+ c172 2,760+ c153 2,764+ c220 2,772+ c215 2,776+ c180 3,443- c187 3,449- c175 3,461- c157 3,487- c222 3,493- c197 3,452+ c195 3,463+ c200 3,479+ c197 3,497+ c191 3,499+ c238 5,311- c173 5,313- c210 5,317- c194 5,319- c182 5,323- c186 5,311+ c159 5,313+ c197 5,314+ c179 5,331+ c193 5,346+ c174 6,263- c196 6,281- c162 6,283- c173 6,299- c155 6,305- c155 6,271+ c195 6,274+ c191 6,283+ c193 6,284+ c168 6,287+ c154 7,257- c192 7,259- c175 7,263- c161 7,269- c224 7,271- c214 7,257+ c189 7,268+ c185 7,277+ c165 7,281+ c193 7,284+ c201 10,239- c228 10,241- c229 10,257- c241 10,263- c216 10,269- c233 10,226+ c197 10,229+ c164 10,232+ c160 10,236+ c193 10,238+ c152 11,227- c195 11,229- c217 11,233- c181 11,235- c182 11,239- c246 11,218+ c147 11,220+ c147 11,224+ c194 11,226+ c222 11,233+ c200 12,227- c197 12,229- c242 12,233- c215 12,239- c255 12,241- c260 12,227+ c213 12,229+ c158 12,232+ c181 12,236+ c151 12,242+ c209