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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 1 |
| 3 | -1 |
| 4 | 9 |
| 5 | -33 |
| 6 | 235 |
| 7 | -1517 |
| 8 | 12593 |
| 9 | -111465 |
| 10 | 1122819 |
| 11 | -12313409 |
| 12 | 147949593 |
| 13 | -1922353925 |
| 14 | 26918452691 |
| 15 | -403744456541 |
| 16 | 6460109224801 |
| 17 | -109820584161393 |
| 18 | 1976779056442179 |
| 19 | -37558742545087481 |
[1,0,1,-1,9,-33,235,-1517,12593,-111465,1122819, -12313409,147949593,-1922353925,26918452691, -403744456541,6460109224801,-109820584161393, 1976779056442179,-37558742545087481] |