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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 8 |
| 4 | 42 |
| 5 | 360 |
| 6 | 4800 |
| 7 | 102960 |
| 8 | 3538080 |
| 9 | 196035840 |
| 10 | 17520703200 |
| 11 | 2529842515200 |
| 12 | 590412901478400 |
| 13 | 222813349683724800 |
| 14 | 136001024583142118400 |
| 15 | 134285149587387262464000 |
| 16 | 214504624277084224347264000 |
| 17 | 554361997358383529330695680000 |
[1,2,8,42,360,4800,102960,3538080,196035840, 17520703200,2529842515200,590412901478400, 222813349683724800,136001024583142118400, 134285149587387262464000, 214504624277084224347264000, 554361997358383529330695680000] |