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| n | a(n) |
|---|---|
| 1 | 8 |
| 2 | 128 |
| 3 | 1416 |
| 4 | 13568 |
| 5 | 119960 |
| 6 | 1009440 |
| 7 | 8205656 |
| 8 | 65068352 |
| 9 | 506193144 |
| 10 | 3879735776 |
| 11 | 29378067080 |
| 12 | 220265711040 |
| 13 | 1637726387096 |
| 14 | 12091336503584 |
| 15 | 88727095777896 |
| 16 | 647661676223168 |
| 17 | 4705654523841704 |
| 18 | 34049855885188128 |
| 19 | 245482626441965048 |
| 20 | 1764039730476165824 |
[8,128,1416,13568,119960,1009440,8205656,65068352, 506193144,3879735776,29378067080,220265711040, 1637726387096,12091336503584,88727095777896, 647661676223168,4705654523841704, 34049855885188128,245482626441965048, 1764039730476165824] |