n个------------------------------------------
0 2........................................2
1 1001.....................................9
2 1000001.................................65
3 1000000001.............................513
4 1000000000001.........................4097
5 1000000000000001.....................32769
6 1000000000000000001.................262145
7 1000000000000000000001.............2097153
8 1000000000000000000000001.........16777217
9 1000000000000000000000000001.....134217729