List of champions for factoring Cunningham numbers: Special number field sieve: 3409 C158 2,523- A. K. Lenstra & D. Bernstein with two MasPars 3071 C148 2,512+ A. K. Lenstra & M. Manasse with several computers Largest penultimate prime factor (ultimate factor shown also): 3409 p69*p90 2,523- A. K. Lenstra & D. Bernstein with two MasPars 3524 p61*p62 3,293+ R. Silverman with several computers First five holes in each table on June 23, 1993: 2,511- c123 2,527- c145 2,529- c101 2,539- c127 2,543- c106 2,519+ c104 2,521+ c140 2,535+ c101 2,569+ c144 2,575+ c102 2,854M c102 2,874M c102 2,898L c107 2,898M c115 2,902M c111 2,524+ c119 2,536+ c156 2,548+ c157 2,556+ c134 2,568+ c120 3,319- c119 3,331- c139 3,349- c167 3,359- c108 3,365- c111 3,307+ c137 3,311+ c111 3,313+ c129 3,314+ c106 3,316+ c127 5,233- c148 5,247- c147 5,253- c143 5,273- c101 5,277- c186 5,193+ c124 5,206+ c143 5,209+ c108 5,213+ c98 5,214+ c122 6,173- c119 6,187- c107 6,199- c122 6,209- c111 6,211- c142 6,176+ c125 6,178+ c137 6,202+ c142 6,206+ c146 6,209+ c130 7,169- c132 7,173- c146 7,187- c121 7,193- c109 7,199- c164 7,163+ c117 7,172+ c114 7,173+ c123 7,178+ c146 7,181+ c114 10,163- c138 10,167- c142 10,169- c152 10,173- c154 10,177- c113 10,149+ c123 10,158+ c153 10,163+ c139 10,166+ c164 10,167+ c118 11,151- c139 11,167- c128 11,169- c151 11,177- c104 11,179- c133 11,127+ c120 11,131+ c129 11,142+ c141 11,146+ c132 11,148+ c147 12,137- c123 12,139- c119 12,149- c156 12,151- c162 12,161- c135 12,148+ c156 12,151+ c128 12,155+ c111 12,157+ c106 12,163+ c132 Here is the list of smaller but needed numbers: 2,529- c101 2,519+ c104 2,535+ c101 2,575+ c102 2,854M c102 2,874M c102 2,926L c103 2,588+ c97 5,213+ c98