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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 35 |
| 5 | 251 |
| 6 | 2602 |
| 7 | 30900 |
| 8 | 400818 |
| 9 | 5401599 |
| 10 | 74617105 |
| 11 | 1047497078 |
| 12 | 14888851869 |
[1,2,6,35,251,2602,30900,400818,5401599,74617105, 1047497078,14888851869] |