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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | -1 |
| 3 | 3 |
| 4 | -18 |
| 5 | 60 |
| 6 | -60 |
| 7 | -1890 |
| 8 | 31472 |
| 9 | -319032 |
| 10 | 2369280 |
| 11 | -6374280 |
| 12 | -209401368 |
| 13 | 5594400240 |
| 14 | -90523285944 |
| 15 | 1016295254520 |
| 16 | -3922383447232 |
| 17 | -184920315173888 |
| 18 | 6878045401558272 |
| 19 | -151394798389814208 |
[1,0,-1,3,-18,60,-60,-1890,31472,-319032,2369280, -6374280,-209401368,5594400240,-90523285944, 1016295254520,-3922383447232,-184920315173888, 6878045401558272,-151394798389814208] |