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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | -2 |
| 3 | 9 |
| 4 | -51 |
| 5 | 384 |
| 6 | -3506 |
| 7 | 38126 |
| 8 | -479770 |
| 9 | 6872392 |
| 10 | -110410296 |
| 11 | 1967181840 |
| 12 | -38502498592 |
| 13 | 821352161200 |
| 14 | -18969587297792 |
| 15 | 471608373782864 |
| 16 | -12558441874756176 |
| 17 | 356636706706414848 |
| 18 | -10759204665600245888 |
[0,1,-2,9,-51,384,-3506,38126,-479770,6872392, -110410296,1967181840,-38502498592,821352161200, -18969587297792,471608373782864, -12558441874756176,356636706706414848, -10759204665600245888] |