VB练习题,,请高手帮我完成 a=(2n+1)!,n is an positive integer

Dim n As Integer
Private Sub Form_Click()
Dim i As Integer
Dim j As Long
j = 1
For i = 1 To n
j = j * 2 * i * (2 * i + 1)
Next i
Print j
End Sub
Private Sub Form_Load()
n = InputBox("请输入n的数值：")
End Su