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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | -2 |
| 2 | 20 |
| 3 | -16 |
| 4 | 14096 |
| 5 | 887456 |
| 6 | 126998976 |
| 7 | 21834514688 |
| 8 | 5067177011456 |
| 9 | 1485621376751104 |
| 10 | 540527763829711872 |
| 11 | 238770291840873000960 |
| 12 | 125924968135743519723520 |
| 13 | 78156500138405011699867648 |
[1,-2,20,-16,14096,887456,126998976,21834514688, 5067177011456,1485621376751104,540527763829711872, 238770291840873000960,125924968135743519723520, 78156500138405011699867648] |