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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | -3 |
| 4 | 11 |
| 5 | -50 |
| 6 | 214 |
| 7 | -504 |
| 8 | -6252 |
| 9 | 162576 |
| 10 | -2754684 |
| 11 | 42663060 |
| 12 | -650722260 |
| 13 | 10034523720 |
| 14 | -158078985000 |
| 15 | 2553082867440 |
| 16 | -42265263885600 |
| 17 | 715134876153600 |
| 18 | -12299306666944560 |
| 19 | 213041497002431760 |
| 20 | -3658374963886842000 |
| 21 | 60422495064228108000 |
[0,0,1,-3,11,-50,214,-504,-6252,162576,-2754684, 42663060,-650722260,10034523720,-158078985000, 2553082867440,-42265263885600,715134876153600, -12299306666944560,213041497002431760, -3658374963886842000,60422495064228108000] |