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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | -1 |
| 3 | 1 |
| 4 | -2 |
| 5 | 25 |
| 6 | -136 |
| 7 | 761 |
| 8 | -4752 |
| 9 | 42065 |
| 10 | -386176 |
| 11 | 3898321 |
| 12 | -42551552 |
| 13 | 521329705 |
| 14 | -6816879616 |
| 15 | 96017526281 |
| 16 | -1446339889152 |
| 17 | 23356125062945 |
| 18 | -399659935891456 |
| 19 | 7240133620964641 |
| 20 | -138393644469911552 |
| 21 | 2786977252450841785 |
[0,1,-1,1,-2,25,-136,761,-4752,42065,-386176, 3898321,-42551552,521329705,-6816879616, 96017526281,-1446339889152,23356125062945, -399659935891456,7240133620964641, -138393644469911552,2786977252450841785] |