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Old 2008-05-27, 15:45   #3
R. Gerbicz
 
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"Robert Gerbicz"
Oct 2005
Hungary

32·52·7 Posts
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Quote:
Originally Posted by Housemouse View Post
If P is an even perfect number greater than 6, P-1 is always composite divisible by nine. Is it known which perfect numbers are prime for P+1?
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