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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | -1 |
| 3 | -2 |
| 4 | 1 |
| 5 | 5 |
| 6 | 12 |
| 7 | 48 |
| 8 | 245 |
| 9 | 1523 |
| 10 | 11195 |
| 11 | 94386 |
| 12 | 895924 |
| 13 | 9443452 |
| 14 | 109355276 |
| 15 | 1379316576 |
| 16 | 18815818845 |
| 17 | 275948260895 |
| 18 | 4328795250501 |
| 19 | 72315318795090 |
| 20 | 1281585812804169 |
| 21 | 24013020062918277 |
| 22 | 474262523193016548 |
| 23 | 9846736220736305136 |
| 24 | 214393809037175108556 |
[1,1,-1,-2,1,5,12,48,245,1523,11195,94386,895924, 9443452,109355276,1379316576,18815818845, 275948260895,4328795250501,72315318795090, 1281585812804169,24013020062918277, 474262523193016548,9846736220736305136, 214393809037175108556] |