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| n | a(n) |
|---|---|
| 2 | 1 |
| 3 | 2 |
| 4 | 5 |
| 5 | 13 |
| 6 | 59 |
| 7 | 285 |
| 8 | 1987 |
| 9 | 16057 |
| 10 | 149430 |
| 11 | 1551863 |
| 12 | 17747299 |
| 13 | 221015026 |
[1,2,5,13,59,285,1987,16057,149430,1551863, 17747299,221015026] |