参考答案

Dim a(50) As Long
Private Sub Command1_Click()
    Dim f As Long
    a(1) = 1
    a(2) = 1
    For i = 3 To Val(Text1.Text)
      f = a(i - 2) + a(i - 1) + 1
      a(i) = f
    Next
    Text2.Text = f
End Sub
Private Sub Command2_Click()
    Open App.Path & "\out5.txt" For Output As #1
    Print #1, Text2.Text
    Close #1
End Sub
Private Sub Form_Load()
End Sub