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Old 2017-10-14, 02:10   #2
science_man_88
 
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"Forget I exist"
Jul 2009
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Quote:
Originally Posted by ThomRuley View Post
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
http://www.lirmm.fr/~ochem/opn/ links to the paper I think you are reading, and gives one example, that I can't quite get my head around.
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