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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 2 |
| 3 | -3 |
| 4 | 32 |
| 5 | -150 |
| 6 | 1404 |
| 7 | -11340 |
| 8 | 120448 |
| 9 | -1319976 |
| 10 | 16600320 |
| 11 | -223664760 |
| 12 | 3300331704 |
| 13 | -52223268240 |
| 14 | 887583503520 |
| 15 | -16071609481200 |
| 16 | 309263446333440 |
| 17 | -6296705309543040 |
| 18 | 135262191966465600 |
| 19 | -3056359409652695040 |
| 20 | 72462969268541596800 |
[1,0,2,-3,32,-150,1404,-11340,120448,-1319976, 16600320,-223664760,3300331704,-52223268240, 887583503520,-16071609481200,309263446333440, -6296705309543040,135262191966465600, -3056359409652695040,72462969268541596800] |