VB編程計算下列公式的值，其中n (<15)為從鍵盤輸入的正整數。 S=1!+3!+5!+……+(2*n-1)! 急求謝謝！

Dim n As Integer, i As Integer

Dim sum As Double

n = Val(InputBox("Please Enter N:"))

sum = 0

For i = 1 To n

sum = sum + fac(2 * i - 1)

Next i

Print sum

End Sub

Function fac(n As Integer) As Double

Dim f As Double

f = 1#

For i = 1 To n

f = f * i

Next i

fac = f

End Function