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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 4 |
| 4 | 35 |
| 5 | 332 |
| 6 | 3766 |
| 7 | 45417 |
| 8 | 579428 |
| 9 | 7668281 |
| 10 | 104572251 |
| 11 | 1460486828 |
[1,1,4,35,332,3766,45417,579428,7668281,104572251, 1460486828] |