Originally Posted by ThomRuley
I've been reading a couple of papers lately about the OPN problem. I understand how proof trees work, but I still have a question about the more detailed parts of it. I notice that Brent et al had a list of forbidden factors, as do Ochem and Rao.
Brent et al
127,19,7,11,31,13,3,5
Ochem and Rao
127,19,7,11,331,31,97,61,13,398581,1093,3,5,307,17
I still don't understand why were "forbidden" in the proof trees. Is it similar to Kishore 1983, where an OPN not divisible by 3 has more prime factors?
Thanks
