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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 8 |
| 5 | 33 |
| 6 | 187 |
| 7 | 1120 |
| 8 | 7418 |
| 9 | 50730 |
| 10 | 359234 |
| 11 | 2598893 |
| 12 | 19165186 |
| 13 | 143499135 |
[1,1,2,8,33,187,1120,7418,50730,359234,2598893, 19165186,143499135] |