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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | -1 |
| 3 | 6 |
| 4 | -22 |
| 5 | 120 |
| 6 | -856 |
| 7 | 7056 |
| 8 | -68272 |
| 9 | 758400 |
| 10 | -9452416 |
| 11 | 130918656 |
| 12 | -1995427072 |
| 13 | 33173038080 |
| 14 | -597434776576 |
| 15 | 11587651270656 |
| 16 | -240801628444672 |
| 17 | 5337660866396160 |
| 18 | -125710803524878336 |
| 19 | 3134856182239789056 |
[0,1,-1,6,-22,120,-856,7056,-68272,758400, -9452416,130918656,-1995427072,33173038080, -597434776576,11587651270656,-240801628444672, 5337660866396160,-125710803524878336, 3134856182239789056] |