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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | -1 |
| 3 | 0 |
| 4 | -4 |
| 5 | 40 |
| 6 | -181 |
| 7 | 896 |
| 8 | -8464 |
| 9 | 88320 |
| 10 | -863041 |
| 11 | 9382912 |
| 12 | -120330244 |
| 13 | 1676579840 |
| 14 | -24638823301 |
| 15 | 390142722048 |
| 16 | -6678730634944 |
| 17 | 121851014348800 |
| 18 | -2353418855768161 |
| 19 | 48123147849826304 |
| 20 | -1039698070255280164 |
[0,1,-1,0,-4,40,-181,896,-8464,88320,-863041, 9382912,-120330244,1676579840,-24638823301, 390142722048,-6678730634944,121851014348800, -2353418855768161,48123147849826304, -1039698070255280164] |