[0,1]  [1,0]  [2,0]  [3,0]  [4,15]  [5,0]  [6,32]  [7,0]  [8,15]  [9,0]  [10,0]  [11,0]  [12,1]
  i                              A_i
  0                                1
  4                               15
  6                               32
  8                               15
 12                                1