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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 3 |
| 4 | 6 |
| 5 | 24 |
| 6 | 51 |
| 7 | 251 |
| 8 | 3121 |
| 9 | 42613 |
| 10 | 23023556 |
| 11 | 143130479 |
| 12 | 2602986161967491 |
[1,2,3,6,24,51,251,3121,42613,23023556,143130479, 2602986161967491] |