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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 2 |
| 3 | -3 |
| 4 | 16 |
| 5 | -50 |
| 6 | 248 |
| 7 | -504 |
| 8 | -1584 |
| 9 | 94536 |
| 10 | -1464768 |
| 11 | 23328360 |
| 12 | -336539040 |
| 13 | 5198852880 |
| 14 | -79862710800 |
| 15 | 1306170600840 |
| 16 | -21763435223040 |
| 17 | 382939844024640 |
| 18 | -6915154663557120 |
| 19 | 130859230589792640 |
[0,0,2,-3,16,-50,248,-504,-1584,94536,-1464768, 23328360,-336539040,5198852880,-79862710800, 1306170600840,-21763435223040,382939844024640, -6915154663557120,130859230589792640] |