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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 0 |
| 3 | 2 |
| 4 | -3 |
| 5 | 27 |
| 6 | -91 |
| 7 | 723 |
| 8 | -3555 |
| 9 | 28338 |
| 10 | -174027 |
| 11 | 1440582 |
| 12 | -10280631 |
| 13 | 89422482 |
| 14 | -713833016 |
| 15 | 6548902473 |
| 16 | -57199453969 |
| 17 | 553760916426 |
| 18 | -5219453249126 |
| 19 | 53271930913793 |
| 20 | -536862065044303 |
| 21 | 5767357558711960 |
| 22 | -61733919421613462 |
[1,1,0,2,-3,27,-91,723,-3555,28338,-174027, 1440582,-10280631,89422482,-713833016,6548902473, -57199453969,553760916426,-5219453249126, 53271930913793,-536862065044303,5767357558711960, -61733919421613462] |