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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | -1 |
| 3 | -3 |
| 4 | 8 |
| 5 | 25 |
| 6 | -121 |
| 7 | -427 |
| 8 | 3128 |
| 9 | 12465 |
| 10 | -124921 |
| 11 | -555731 |
| 12 | 7158128 |
| 13 | 35135945 |
| 14 | -557749921 |
| 15 | -2990414715 |
| 16 | 56767019408 |
| 17 | 329655706465 |
| 18 | -7316056402321 |
| 19 | -45692713833379 |
| 20 | 1164842760597368 |
| 21 | 7777794952988025 |
| 22 | -224574978081433321 |
[0,1,-1,-3,8,25,-121,-427,3128,12465,-124921, -555731,7158128,35135945,-557749921,-2990414715, 56767019408,329655706465,-7316056402321, -45692713833379,1164842760597368,7777794952988025, -224574978081433321] |