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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 3 |
| 4 | -4 |
| 5 | -50 |
| 6 | -36 |
| 7 | 2058 |
| 8 | 10800 |
| 9 | -131616 |
| 10 | -1975680 |
| 11 | 7741800 |
| 12 | 417480480 |
| 13 | 1307617584 |
| 14 | -101626746144 |
| 15 | -1284067345680 |
| 16 | 25419094122240 |
| 17 | 791333924647680 |
| 18 | -3900043588999680 |
| 19 | -472446912421801728 |
| 20 | -3183064994777932800 |
[1,1,2,3,-4,-50,-36,2058,10800,-131616,-1975680, 7741800,417480480,1307617584,-101626746144, -1284067345680,25419094122240,791333924647680, -3900043588999680,-472446912421801728, -3183064994777932800] |