1. (2019·浙江模拟) 【加试题】有如下程序段：

Dim a(1 to 20) As Integer

For i=2 to 10

For j=2 to 20\i

a(i*j)=a(i*j) +1

Next j

Next i

该程序段运行后，数组a中元素值为0的个数是（  ）