Public Class Form1
    Private Sub Command1_Click()
        Dim n As Integer  'Number of rows
        Dim i, j As Integer 'Counters
        n = Val(TextBox1.Text)
        For i = 0 To n - 1
            'Label1.Text += (Space(n - i)) add this if label is not centered
            For j = 0 To i
                Label1.Text += (Trim(Str(nCr(i, j))) + "       ")

            Next j
            Label1.Text += vbNewLine
        Next i
    End Sub
    Private Function nCr(ByVal n As Integer, ByVal r As Integer) As Long
        If (n = r) Then
            nCr = 1
        Else
            nCr = Factorial(n) / (Factorial(n - r) * Factorial(r))
        End If
    End Function

    Private Function Factorial(ByVal n As Integer) As Long
        Dim i As Integer
        Factorial = 1
        If n <> 0 Then
            For i = 2 To n
                Factorial = Factorial * i
            Next i
        End If
    End Function

    Private Sub TextBox1_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox1.TextChanged
        Label1.Text = Nothing
        If Val(TextBox1.Text) > 20 Then
            Label1.Text = "(Number between 1 and 20)"
        ElseIf Val(TextBox1.Text) < 1 Then
            Label1.Text = "(Number between 1 and 20)"
        Else
            Command1_Click()
        End If

    End Sub

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

    End Sub
End Class