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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 4 |
| 3 | 33 |
| 4 | 263 |
| 5 | 4775 |
| 6 | 128981 |
| 7 | 5306951 |
| 8 | 387751453 |
| 9 | 43916084516 |
| 10 | 8188708881446 |
[1,4,33,263,4775,128981,5306951,387751453, 43916084516,8188708881446] |