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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | -1 |
| 2 | 1 |
| 3 | -6 |
| 4 | 24 |
| 5 | -117 |
| 6 | 700 |
| 7 | -4947 |
| 8 | 39760 |
| 9 | -358682 |
| 10 | 3594084 |
| 11 | -39598866 |
| 12 | 475774299 |
| 13 | -6191078998 |
| 14 | 86742689434 |
| 15 | -1301964957707 |
| 16 | 20842304366686 |
| 17 | -354473010919852 |
| 18 | 6382843971860354 |
| 19 | -121311619900081996 |
| 20 | 2426875912883720386 |
| 21 | -50976050128395861672 |
[1,-1,1,-6,24,-117,700,-4947,39760,-358682, 3594084,-39598866,475774299,-6191078998, 86742689434,-1301964957707,20842304366686, -354473010919852,6382843971860354, -121311619900081996,2426875912883720386, -50976050128395861672] |