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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 11 |
| 3 | 135 |
| 4 | 4543 |
| 5 | 368720 |
| 6 | 76657600 |
| 7 | 40337678992 |
| 8 | 53581963873035 |
| 9 | 180182113404833816 |
| 10 | 1531920692297677424230 |
| 11 | 32940396032569628105781490 |
| 12 | 1791350856665706531145980060981 |
[2,11,135,4543,368720,76657600,40337678992, 53581963873035,180182113404833816, 1531920692297677424230,32940396032569628105781490, 1791350856665706531145980060981] |