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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | -3 |
| 4 | 7 |
| 5 | -20 |
| 6 | 102 |
| 7 | -658 |
| 8 | 4364 |
| 9 | -32736 |
| 10 | 293760 |
| 11 | -2954512 |
| 12 | 31998048 |
| 13 | -377807040 |
| 14 | 4885788992 |
| 15 | -68173993856 |
| 16 | 1016048413440 |
| 17 | -16157627437056 |
| 18 | 273596846948352 |
| 19 | -4908327247431680 |
| 20 | 92923391633776640 |
| 21 | -1852316352709746688 |
[0,0,1,-3,7,-20,102,-658,4364,-32736,293760, -2954512,31998048,-377807040,4885788992, -68173993856,1016048413440,-16157627437056, 273596846948352,-4908327247431680, 92923391633776640,-1852316352709746688] |