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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 8 |
| 3 | 216 |
| 4 | 19584 |
| 5 | 5542200 |
| 6 | 4551802560 |
| 7 | 10225942680240 |
| 8 | 60077099766620160 |
[1,8,216,19584,5542200,4551802560,10225942680240, 60077099766620160] |