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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | -1 |
| 2 | 1 |
| 3 | -3 |
| 4 | 13 |
| 5 | -65 |
| 6 | 389 |
| 7 | -2723 |
| 8 | 21785 |
| 9 | -196065 |
| 10 | 1960649 |
| 11 | -21567139 |
| 12 | 258805669 |
| 13 | -3364473697 |
| 14 | 47102631757 |
| 15 | -706539476355 |
| 16 | 11304631621681 |
| 17 | -192178737568577 |
| 18 | 3459217276234385 |
| 19 | -65725128248453315 |
| 20 | 1314502564969066301 |
[1,-1,1,-3,13,-65,389,-2723,21785,-196065,1960649, -21567139,258805669,-3364473697,47102631757, -706539476355,11304631621681,-192178737568577, 3459217276234385,-65725128248453315, 1314502564969066301] |