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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | -5 |
| 4 | -31 |
| 5 | -99 |
| 6 | 1201 |
| 7 | 13231 |
| 8 | 70785 |
| 9 | -1362311 |
| 10 | -21562399 |
| 11 | -161746749 |
| 12 | 4263108961 |
| 13 | 87979472725 |
| 14 | 849097038609 |
| 15 | -28416142768649 |
| 16 | -723086288422399 |
| 17 | -8532476619366159 |
| 18 | 346207723221680065 |
| 19 | 10474480743776327179 |
| 20 | 146105160034616914401 |
[1,1,1,-5,-31,-99,1201,13231,70785,-1362311, -21562399,-161746749,4263108961,87979472725, 849097038609,-28416142768649,-723086288422399, -8532476619366159,346207723221680065, 10474480743776327179,146105160034616914401] |