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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 8 |
| 3 | 120 |
| 4 | 2288 |
| 5 | 49680 |
| 6 | 1170968 |
| 7 | 29206632 |
| 8 | 759265760 |
| 9 | 20371816992 |
| 10 | 560386232744 |
[1,8,120,2288,49680,1170968,29206632,759265760, 20371816992,560386232744] |