急求用vb求1！+3！+5！+.......+(2n-1)! 的代码

Dim a, sum
Dim n%
a = 1
sum = 1
n = InputBox("输入N")
For i = 3 To 2 * n - 1 Step 2
a = a * (i - 1) * i
sum = sum + a
Next i
Print sum

楼上回答的很好，补充一下：
Dim a, sum, n As Integer

Private Sub Form_Click()
a = 1
sum = 1
n = InputBox("输入N")
For i = 3 To 2 * n - 1 Step 2
a = a * (i - 1) * i
sum = sum + a
Next i
Print sum
End Sub