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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 2 |
| 5 | 6 |
| 6 | 109 |
| 7 | 23746 |
| 8 | 106228849 |
| 9 | 9365022303540 |
| 10 | 20890436195945769617 |
| 11 | 1478157455158044452849321016 |
[0,1,1,1,2,6,109,23746,106228849,9365022303540, 20890436195945769617,1478157455158044452849321016] |