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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 8 |
| 3 | 42 |
| 4 | 456 |
| 5 | 4800 |
| 6 | 69840 |
| 7 | 1093680 |
| 8 | 20482560 |
| 9 | 420577920 |
| 10 | 9736070400 |
| 11 | 245887488000 |
| 12 | 6806133734400 |
| 13 | 203555082931200 |
| 14 | 6565920180019200 |
| 15 | 226728504946944000 |
| 16 | 8355118608764928000 |
| 17 | 327047476385710080000 |
[1,1,8,42,456,4800,69840,1093680,20482560, 420577920,9736070400,245887488000,6806133734400, 203555082931200,6565920180019200, 226728504946944000,8355118608764928000, 327047476385710080000] |