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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 8 |
| 3 | 54 |
| 4 | 480 |
| 5 | 5400 |
| 6 | 72720 |
| 7 | 1144080 |
| 8 | 20563200 |
| 9 | 415860480 |
| 10 | 9344160000 |
| 11 | 230958604800 |
| 12 | 6227499801600 |
| 13 | 181909958630400 |
| 14 | 5722470212659200 |
| 15 | 192874123233792000 |
| 16 | 6934147333521408000 |
| 17 | 264875092391669760000 |
[1,2,8,54,480,5400,72720,1144080,20563200, 415860480,9344160000,230958604800,6227499801600, 181909958630400,5722470212659200, 192874123233792000,6934147333521408000, 264875092391669760000] |