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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 1 |
| 3 | 18 |
| 4 | 262 |
| 5 | 3393 |
| 6 | 39541 |
| 7 | 421863 |
| 8 | 4457974 |
| 9 | 46853770 |
| 10 | 482301801 |
| 11 | 4931928485 |
[0,1,1,18,262,3393,39541,421863,4457974,46853770, 482301801,4931928485] |