Help for this page

Select Code to Download


  1. or download this
    0 + 1 + 2 + .. + ($n-1)
    
  2. or download this
    $n * ($n-1) / 2
    
  3. or download this
    ( 0 + 1 + 2 + .. + ($n-1) ) / $n
    
  4. or download this
    ($n-1) / 2