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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | -1 |
| 3 | -6 |
| 4 | -31 |
| 5 | -140 |
| 6 | -577 |
| 7 | -1498 |
| 8 | 6785 |
| 9 | 192840 |
| 10 | 2667711 |
| 11 | 31783730 |
| 12 | 353106657 |
| 13 | 3771795196 |
| 14 | 38270910975 |
| 15 | 356214219678 |
| 16 | 2639000258561 |
| 17 | 4515406498320 |
| 18 | -420731049845121 |
| 19 | -13553517751217174 |
| 20 | -318084517098105631 |
[1,0,-1,-6,-31,-140,-577,-1498,6785,192840, 2667711,31783730,353106657,3771795196,38270910975, 356214219678,2639000258561,4515406498320, -420731049845121,-13553517751217174, -318084517098105631] |