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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 5 |
| 3 | 20 |
| 4 | 101 |
| 5 | 751 |
| 6 | 5949 |
| 7 | 49010 |
| 8 | 418366 |
| 9 | 3627049 |
| 10 | 32067600 |
| 11 | 287357618 |
[0,5,20,101,751,5949,49010,418366,3627049, 32067600,287357618] |