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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 11 |
| 5 | 33 |
| 6 | 150 |
| 7 | 986 |
| 8 | 11416 |
| 9 | 245440 |
| 10 | 10164119 |
| 11 | 793907916 |
| 12 | 114150623175 |
| 13 | 29709609171994 |
[1,2,4,11,33,150,986,11416,245440,10164119, 793907916,114150623175,29709609171994] |