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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 0 |
| 4 | 12 |
| 5 | 18 |
| 6 | 624 |
| 7 | 6012 |
| 8 | 228984 |
| 9 | 8210664 |
| 10 | 619049280 |
| 11 | 63783422784 |
| 12 | 11382530540616 |
[0,1,0,12,18,624,6012,228984,8210664,619049280, 63783422784,11382530540616] |