有如下VB程序段：
a(1) = 1: a(2) = 1 b(1) = 1: b(2) = 2 For i = 3 To 5 a(i) = a(i - 1) + a(i - 2) b(i) = b(i - 1) + a(i) Next i
执行该程序段后，数组元素b(5)的值为
12
8
5
15
