回复：If the total people is 7, what is the number of 3+4 part? Is

C(7,3)(4!/4)(3!/3)+7!/7=1140.

8 P, C(8,3)(5!/5)(3!/3)+C(8,4)/2!(4!/4)^2+8!/8, please note 2 and 2!. 

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• thanks. So the general solution should be -wxcfan123- ♂ (416 bytes) () 05/06/2012 postreply 08:28:32

• F(N) = SUM_(n1 + n2 + ... nk=N, ni >=3 ) {[C(N, n1)C(N-n1,n2).. -jinjing- ♀ (66 bytes) () 05/06/2012 postreply 09:37:01

• ... {[C(N, n1)C(N-n1,n2)..C(N-n1-n2-...n(k-1,nk)/D(n1,n2m,,,nk)] -jinjing- ♀ (0 bytes) () 05/06/2012 postreply 09:41:59