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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 6 |
| 3 | 63 |
| 4 | 958 |
| 5 | 19254 |
| 6 | 484735 |
| 7 | 14759358 |
| 8 | 530271461 |
| 9 | 22073719357 |
| 10 | 1049789517047 |
| 11 | 56406216212727 |
[1,1,6,63,958,19254,484735,14759358,530271461, 22073719357,1049789517047,56406216212727] |