数组开始:
1, 3, 15, 81, 459, 2673, 15849, ...
6, 33, 189, 1107, 6588, 39663, 240894, ...
60, 378, 2349, 14553, 90207, 560115, 3485187, ...
675, 4509, 29403, 189351, 1211031, 7715331, 49045662, ...
7992, 55188, 371358, 2458998, 16112925, 104838219, 678790125, ...
...