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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | -1 |
| 3 | 0 |
| 4 | -6 |
| 5 | 23 |
| 6 | -135 |
| 7 | 1288 |
| 8 | -10164 |
| 9 | 106661 |
| 10 | -1257165 |
| 11 | 15497152 |
| 12 | -222045450 |
| 13 | 3414340811 |
| 14 | -56743257571 |
| 15 | 1031328757912 |
| 16 | -19972120728840 |
| 17 | 414440475923689 |
| 18 | -9175579196399001 |
| 19 | 215060308589382272 |
[0,1,-1,0,-6,23,-135,1288,-10164,106661,-1257165, 15497152,-222045450,3414340811,-56743257571, 1031328757912,-19972120728840,414440475923689, -9175579196399001,215060308589382272] |