2状态概率 (n+1) n 由此列出平衡方程: nP=uP Pn-1+(n+1)O+1=(元+n)Pn,n<C nP-I+Cup=(+CuP, n2C2. 状态概率 2 n ( 1) n + C C C C 0 1 1 1 1 1 ( 1) ( ) ( ) n n n n- n n P P P n P n P n C P C P C P n C − + + = + + = + + = + , , 由此列出平衡方程: 2 ... n C n+1 C-1 C+1 0 1 n-1 ... ... n-1 n n+1