   ! 6 ! 8  2)! - (n ! n  ! 4 ! 5     ! 10 ! 10 ! 11 + ...

   ! 6 ! 8  2)! - (n ! n  ! 4 ! 5     ! 10 ! 10 ! 11 +    5 ! 4 ! 4 5 ! 4 ! 5 = ⋅ =  56 ! 6 ! 6 7 8 ! 6 ! 8 = ⋅⋅ =  ( ) 12 ! 10 111! 10 !10 ! 10 ! 10 11 ! 10 ! 10 ! 11 = + = +⋅ = +  ( ) ( ) ( ) nn ! 2 - n ! 2 - n 1 - n n 2)! - (n ! n 2 −= ⋅ =      ∴== 30 2)! - (n ! 2) - n ( 1) - n ( n 30 2)! - (n ! n         ( ) ( ) ( ) ( ) ( ) ( ) ∴⋅= ⋅ ⋅= ⋅    4 ! n ! ) 1n ( - ! ) 2 n ( = ++    ∴= ⋅+⋅++ 4 ! n ! n ) 1 n ( - ! n ! ) 1n ( ! ) 2 n (    [ ] 4 ! n 1- 2 n ) 2 n ( ! n = +⋅+    ∴ ∴  ∴         ! 2 ! 10         