Public Class Form1

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim i, j, n As Integer
        TextBox1.Text = Nothing
        For i = 0 To 3
            For j = 0 To 3
                For n = 0 To 3
                    TextBox1.Text = TextBox1.Text & "i = " & CStr(i) & " j = " & CStr(j) & " n = " & CStr(n) & vbCrLf
                Next
            Next
        Next
    End Sub

    Private Sub TextBox1_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox1.TextChanged

    End Sub
End Class