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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 1 |
| 5 | 1 |
| 6 | 3 |
| 7 | 11 |
| 8 | 27 |
| 9 | 63 |
| 10 | 285 |
| 11 | 1745 |
| 12 | 11867 |
| 13 | 83339 |
| 14 | 729439 |
| 15 | 8174347 |
| 16 | 113015753 |
| 17 | 1872094927 |
| 18 | 37173405545 |
| 19 | 899575608439 |
| 20 | 26450719284143 |
[1,1,1,1,1,3,11,27,63,285,1745,11867,83339,729439, 8174347,113015753,1872094927,37173405545, 899575608439,26450719284143] |