a(3)=分成1/2、2/3或3/4部分的4个分区:
#1: 3/4 + 3/4 + 3/4 + 3/4 = 3,
#2: (3/4 + 3/4) + (1/2 + 1/2 + 1/2) = 3,
#3: (2/3 + 2/3 + 2/3) + (1/2 + 1/2) = 3,
#4: 1/2 + 1/2 + 1/2 + 1/2 + 1/2 + 1/2 = 3;
a(4)=分为1/2、2/3、3/4或4/5部分的7个分区:
#1: 4/5 + 4/5 + 4/5 + 4/5 + 4/5 = 4,
#2: (3/4 + 3/4 + 3/4 + 3/4) + (1/2 + 1/2) = 4,
#3: (3/4 + 3/4) + (2/3 + 2/3 + 2/3) + 1/2 = 4,
#4: (3/4 + 3/4) + (1/2 + 1/2 + 1/2 + 1/2 + 1/2) = 4,
#5: 2/3 + 2/3 + 2/3 + 2/3 + 2/3 + 2/3 = 4,
#6: 2/3 + 2/3 + 2/3 + 1/2 + 1/2 + 1/2 + 1/2 = 4,
#7: 1/2 + 1/2 + 1/2 + 1/2 + 1/2 + 1/2 + 1/2 + 1/2 = 4.
|