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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 3 |
| 4 | 12 |
| 5 | 57 |
| 6 | 304 |
| 7 | 1765 |
| 8 | 10943 |
| 9 | 71519 |
| 10 | 488186 |
| 11 | 3456526 |
| 12 | 25251479 |
| 13 | 189545179 |
[1,1,3,12,57,304,1765,10943,71519,488186,3456526, 25251479,189545179] |