Has something to do with "Pigeon Holing
Geo I don't know if these help. I did a search at google on the formula:
http://www.cs.mtu.edu/~shene/COURSES...06/fact-2.html
This is a word doc:
http://www.cecs.csulb.edu/~lam/cecs228/ch4.doc
I think this is a powerpoint presentation:
file:///D:/Temporary%20Internet%20Files/Temporary%20Internet%20Files/Content.IE5/I56W66T4/275,10,r-permutations
This one seemed the simplest:
http://fclass.vaniercollege.qc.ca/we...ombs_Intro.htm