1.
n . , , . , .
n k (
) , k , , .
n k ( 
)
(1.1)
n! n-
,
0!=1.
n n.
n ( 
)
(1.2)
() n k , k , .
n k ( 
)
(1.3)
n : = 
. k - ( , ), , . , k =4 
.
n k ( 
)
(1.4)
n k : n 1 1- , n 2 2- ,..., nk k - , n 1+ n 2++ nk = n.
- n , .
( Pn (n 1, n 2, nk))
Pn (n 1, n 2, nk)= 
k - ( , ), . , k = 4 
, 
.
n k ( 
)
(1.6)
' .
. ' ' m , ' n , , m + n .
. ' ' m ' n , ' (, ) m× n .
