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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 8 |
| 4 | 84 |
| 5 | 800 |
| 6 | 15360 |
| 7 | 357696 |
| 8 | 6873984 |
| 9 | 262813248 |
| 10 | 12288817152 |
| 11 | 432621305856 |
| 12 | 28148895055872 |
| 13 | 2108257586380800 |
[1,1,8,84,800,15360,357696,6873984,262813248, 12288817152,432621305856,28148895055872, 2108257586380800] |