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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 2 |
| 3 | -3 |
| 4 | 16 |
| 5 | -50 |
| 6 | 608 |
| 7 | -4284 |
| 8 | 53856 |
| 9 | -517824 |
| 10 | 7365312 |
| 11 | -93511440 |
| 12 | 1542037440 |
| 13 | -24197565600 |
| 14 | 452937477120 |
| 15 | -8397165641760 |
| 16 | 176769352058880 |
| 17 | -3770083289172480 |
| 18 | 88455117393715200 |
| 19 | -2127638031857717760 |
[0,0,2,-3,16,-50,608,-4284,53856,-517824,7365312, -93511440,1542037440,-24197565600,452937477120, -8397165641760,176769352058880,-3770083289172480, 88455117393715200,-2127638031857717760] |