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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | -1 |
| 3 | 0 |
| 4 | -6 |
| 5 | 8 |
| 6 | -135 |
| 7 | 448 |
| 8 | -6300 |
| 9 | 35408 |
| 10 | -496125 |
| 11 | 4051168 |
| 12 | -59471874 |
| 13 | 643934744 |
| 14 | -10139836707 |
| 15 | 136494374560 |
| 16 | -2334659166840 |
| 17 | 37300690086560 |
| 18 | -696737113793721 |
| 19 | 12786540011455552 |
| 20 | -260937837571947070 |
[0,0,-1,0,-6,8,-135,448,-6300,35408,-496125, 4051168,-59471874,643934744,-10139836707, 136494374560,-2334659166840,37300690086560, -696737113793721,12786540011455552, -260937837571947070] |