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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | -1 |
| 3 | 4 |
| 4 | -6 |
| 5 | 0 |
| 6 | -150 |
| 7 | 2280 |
| 8 | -16520 |
| 9 | 96320 |
| 10 | -1053360 |
| 11 | 17870400 |
| 12 | -264765600 |
| 13 | 3541824000 |
| 14 | -51903131280 |
| 15 | 904820280000 |
| 16 | -17470217232000 |
| 17 | 351612581299200 |
| 18 | -7290584110742400 |
| 19 | 157383219788121600 |
[0,0,-1,4,-6,0,-150,2280,-16520,96320,-1053360, 17870400,-264765600,3541824000,-51903131280, 904820280000,-17470217232000,351612581299200, -7290584110742400,157383219788121600] |