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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | -2 |
| 3 | 0 |
| 4 | -8 |
| 5 | 40 |
| 6 | -384 |
| 7 | 4144 |
| 8 | -54144 |
| 9 | 815616 |
| 10 | -13958400 |
| 11 | 267218688 |
| 12 | -5657444352 |
| 13 | 131222866944 |
| 14 | -3308765300736 |
| 15 | 90105807790080 |
| 16 | -2635416865112064 |
| 17 | 82388152861360128 |
| 18 | -2741414412289572864 |
| 19 | 96732603325960224768 |
| 20 | -3607731031922910167040 |
[0,1,-2,0,-8,40,-384,4144,-54144,815616,-13958400, 267218688,-5657444352,131222866944,-3308765300736, 90105807790080,-2635416865112064, 82388152861360128,-2741414412289572864, 96732603325960224768,-3607731031922910167040] |