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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 2 |
| 3 | 3 |
| 4 | 8 |
| 5 | 70 |
| 6 | 54 |
| 7 | 1428 |
| 8 | 2624 |
| 9 | 27144 |
| 10 | 158040 |
| 11 | 653400 |
| 12 | 6245832 |
| 13 | 48636432 |
| 14 | -32399472 |
| 15 | 6915245400 |
| 16 | -59561508480 |
| 17 | 1236398222400 |
| 18 | -16660175380416 |
| 19 | 304602764156928 |
| 20 | -5255061417083520 |
[1,0,2,3,8,70,54,1428,2624,27144,158040,653400, 6245832,48636432,-32399472,6915245400, -59561508480,1236398222400,-16660175380416, 304602764156928,-5255061417083520] |