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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 6 |
| 5 | -1 |
| 6 | -58 |
| 7 | -304 |
| 8 | -1090 |
| 9 | -2876 |
| 10 | -4216 |
| 11 | 9244 |
| 12 | 106746 |
| 13 | 529962 |
| 14 | 1874628 |
| 15 | 4669760 |
| 16 | 4309742 |
| 17 | -35179252 |
| 18 | -277928680 |
| 19 | -1269921008 |
| 20 | -4214431912 |
| 21 | -9197175241 |
| 22 | 30113526 |
| 23 | 128659598896 |
| 24 | 822227670866 |
| 25 | 3453484223084 |
| 26 | 10519017940952 |
| 27 | 18490932535144 |
[1,1,2,4,6,-1,-58,-304,-1090,-2876,-4216,9244, 106746,529962,1874628,4669760,4309742,-35179252, -277928680,-1269921008,-4214431912,-9197175241, 30113526,128659598896,822227670866,3453484223084, 10519017940952,18490932535144] |