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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 12 |
| 5 | 36 |
| 6 | 174 |
| 7 | 708 |
| 8 | 4334 |
| 9 | 31424 |
| 10 | 263732 |
| 11 | 2503296 |
| 12 | 26844578 |
| 13 | 316692056 |
| 14 | 4090634212 |
| 15 | 57274447458 |
| 16 | 863488976620 |
[1,1,2,6,12,36,174,708,4334,31424,263732,2503296, 26844578,316692056,4090634212,57274447458, 863488976620] |