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Forum URL: http://www.cut-the-knot.org/cgi-bin/dcforum/forumctk.cgi
Forum Name: Middle school
Topic ID: 48
Message ID: 4
#4, RE: 4!!
Posted by alexb on Oct-11-01 at 08:05 AM
In response to message #3
>is there anywhere that I can find proof of this on the
>internet?

A proof of what? It's a definition of n!!

n!!= n·(n-2)·(n-4)· ...