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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 2 |
| 5 | 3 |
| 6 | 19 |
| 7 | 76 |
| 8 | 476 |
| 9 | 3627 |
| 10 | 30780 |
| 11 | 191122 |
| 12 | 1143877 |
| 13 | 7374982 |
| 14 | 46220204 |
| 15 | 305794362 |
| 16 | 1874323984 |
| 17 | 11217509631 |
| 18 | 68193471721 |
[1,1,2,2,3,19,76,476,3627,30780,191122,1143877, 7374982,46220204,305794362,1874323984,11217509631, 68193471721] |