27 1 , 1 , 2 , 6 ,()
A 21B 22C 23D 24
1,1,2,6,24,() A,25;B,27;C,120;D,125
:2/3,4/9,6/27,() A.1/9B.8/81C.10/81D.12/81
2/3,4/9,6/27,() A.1/9B.8/81C.10/81D.12/81
1,3,2,6, 11, 19, ()A.22B.24C.27D.36
1.2,1.3, 2.6, 6.11,24.18,()A. 25.20B. 120.27C. 32.30D. 36.27
27 9 3 3 ()。A.1 B.2 C.4 D.6