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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | -1 |
| 2 | 2 |
| 3 | 6 |
| 4 | -232 |
| 5 | 4120 |
| 6 | -61488 |
| 7 | 740432 |
| 8 | -3220096 |
| 9 | -224705664 |
| 10 | 11713068800 |
| 11 | -397487915264 |
| 12 | 10466018491392 |
| 13 | -176186211195904 |
| 14 | -2178925657151488 |
| 15 | 399827849856768000 |
| 16 | -24748326426744881152 |
| 17 | 1112888620945558700032 |
| 18 | -36293785214959525625856 |
| 19 | 408738923015995616067584 |
[1,-1,2,6,-232,4120,-61488,740432,-3220096, -224705664,11713068800,-397487915264, 10466018491392,-176186211195904,-2178925657151488, 399827849856768000,-24748326426744881152, 1112888620945558700032,-36293785214959525625856, 408738923015995616067584] |