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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 7 |
| 3 | 31 |
| 4 | 153 |
| 5 | 834 |
| 6 | 4839 |
| 7 | 29612 |
| 8 | 188695 |
| 9 | 1243746 |
| 10 | 8428597 |
| 11 | 58476481 |
| 12 | 413893789 |
| 13 | 2980489256 |
| 14 | 21787216989 |
| 15 | 161374041945 |
| 16 | 1209258743839 |
| 17 | 9155914963702 |
| 18 | 69969663242487 |
| 19 | 539189056700627 |
[1,2,7,31,153,834,4839,29612,188695,1243746, 8428597,58476481,413893789,2980489256,21787216989, 161374041945,1209258743839,9155914963702, 69969663242487,539189056700627] |