TextWindow.Write("Number of rows? ")
r = TextWindow.ReadNumber()
For i = 0 To r - 1
  c = 1
  For k = 0 To i
    TextWindow.CursorLeft = (k + 1) * 4 - Text.GetLength(c)
    TextWindow.Write(c)
    c = c * (i - k) / (k + 1)
  EndFor
  TextWindow.WriteLine("")
EndFor