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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 3 |
| 4 | 3 |
| 5 | 15 |
| 6 | 33 |
| 7 | 9061920 |
| 8 | 1252445414220 |
| 9 | 126032376305404800 |
| 10 | 50110448042127911907268800 |
| 11 | 13399946812028296616282674883512406948355335893125182077721607466200299913000 |
[1,1,1,3,3,15,33,9061920,1252445414220, 126032376305404800,50110448042127911907268800, 13399946812028296616282674883512406948355335893125\ 182077721607466200299913000] |