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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 1 |
| 5 | 2 |
| 6 | 8 |
| 7 | 35 |
| 8 | 403 |
| 9 | 18020 |
| 10 | 7924920 |
| 11 | 146015988543 |
| 12 | 1159796524860801383 |
| 13 | 169358027383278750824815637192 |
| 14 | 196420876345386921523978742421837032517974708496 |
[0,0,1,1,2,8,35,403,18020,7924920,146015988543, 1159796524860801383, 169358027383278750824815637192, 196420876345386921523978742421837032517974708496] |