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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 4 |
| 3 | 10 |
| 4 | 103 |
| 5 | 1487 |
| 6 | 43030 |
| 7 | 2321125 |
| 8 | 232682724 |
| 9 | 43647140344 |
| 10 | 15284990897875 |
| 11 | 9995202105923896 |
| 12 | 12206122815436711870 |
[1,4,10,103,1487,43030,2321125,232682724, 43647140344,15284990897875,9995202105923896, 12206122815436711870] |