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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | -4 |
| 3 | 16 |
| 4 | -64 |
| 5 | 252 |
| 6 | -980 |
| 7 | 3752 |
| 8 | -14076 |
| 9 | 51384 |
| 10 | -180488 |
| 11 | 597812 |
| 12 | -1788936 |
| 13 | 4284828 |
| 14 | -3665376 |
| 15 | -47694524 |
| 16 | 475585724 |
| 17 | -3186717720 |
| 18 | 18465627936 |
| 19 | -98993741736 |
| 20 | 504886869432 |
| 21 | -2484393916472 |
| 22 | 11887606679816 |
| 23 | -55566604265244 |
| 24 | 254411449305096 |
| 25 | -1142492183274444 |
| 26 | 5033985939170544 |
[1,-4,16,-64,252,-980,3752,-14076,51384,-180488, 597812,-1788936,4284828,-3665376,-47694524, 475585724,-3186717720,18465627936,-98993741736, 504886869432,-2484393916472,11887606679816, -55566604265244,254411449305096,-1142492183274444, 5033985939170544] |