View Single Post
Old 2008-05-27, 15:45   #3
R. Gerbicz
 
R. Gerbicz's Avatar
 
"Robert Gerbicz"
Oct 2005
Hungary

101101000102 Posts
Default

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?
http://www.research.att.com/~njas/sequences/A061644
R. Gerbicz is offline   Reply With Quote