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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 2 |
| 4 | 6 |
| 5 | 30 |
| 6 | 330 |
| 7 | 13530 |
| 8 | 5019630 |
| 9 | 69777876630 |
| 10 | 351229105131280530 |
| 11 | 24509789089304573335878465330 |
| 12 | 8608552999157278550998626549630446732052243030 |
[1,2,2,6,30,330,13530,5019630,69777876630, 351229105131280530,24509789089304573335878465330, 8608552999157278550998626549630446732052243030] |