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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 7 |
| 4 | 27 |
| 5 | 143 |
| 6 | 837 |
| 7 | 5529 |
| 8 | 38305 |
| 9 | 276441 |
| 10 | 2042990 |
| 11 | 15396071 |
| 12 | 117761000 |
| 13 | 912100793 |
| 14 | 7139581543 |
| 15 | 56400579759 |
| 16 | 449129924559 |
[1,2,7,27,143,837,5529,38305,276441,2042990, 15396071,117761000,912100793,7139581543, 56400579759,449129924559] |