Recursion tree for n = 256
level  nodes  size  cost/node  level total  total/n^2
    0      1   256      65536        65536   1.000000
    1      3    64       4096        12288   0.187500
    2      9    16        256         2304   0.035156
    3     27     4         16          432   0.006592
    4     81     1          1           81   0.001236
sum of the levels = 80641, T(256) computed directly = 80641

        n            T(n)   T(n)/n^2
        4              19   1.187500
       16             313   1.222656
       64            5035   1.229248
      256           80641   1.230484
     1024         1290499   1.230716
     4096        20648713   1.230759
    16384       330381595   1.230767
    65536      5286112081   1.230769
   262144     84577812979   1.230769
  1048576   1353245066713   1.230769
  4194304  21651921244555   1.230769
 16777216  346430740444321   1.230769
16/13 = 1.230769
