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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | -1 |
| 3 | 1 |
| 4 | 2 |
| 5 | 6 |
| 6 | 10 |
| 7 | 27 |
| 8 | 54 |
| 9 | 253 |
| 10 | 312 |
| 11 | 1116 |
| 12 | 2194 |
| 13 | 6157 |
| 14 | 15552 |
| 15 | 54514 |
| 16 | 89014 |
| 17 | 687252 |
| 18 | 964080 |
| 19 | 2577597 |
| 20 | 6822210 |
| 21 | 22066744 |
| 22 | 38505658 |
| 23 | 119635413 |
| 24 | 289026266 |
| 25 | 517893326 |
| 26 | 2410443144 |
| 27 | 9800259872 |
| 28 | 22806899334 |
| 29 | 87955801599 |
| 30 | 189512770532 |
| 31 | 416815519198 |
| 32 | 1126216162158 |
| 33 | 9805754835374 |
[1,-1,1,2,6,10,27,54,253,312,1116,2194,6157,15552, 54514,89014,687252,964080,2577597,6822210, 22066744,38505658,119635413,289026266,517893326, 2410443144,9800259872,22806899334,87955801599, 189512770532,416815519198,1126216162158, 9805754835374] |