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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 13 |
| 3 | 169 |
| 4 | 936 |
| 5 | 5184 |
| 6 | 33408 |
| 7 | 215296 |
| 8 | 1323792 |
| 9 | 8139609 |
| 10 | 50261301 |
| 11 | 310358689 |
| 12 | 1916465345 |
| 13 | 11834176225 |
| 14 | 73043905820 |
| 15 | 450847788304 |
| 16 | 2783165854192 |
| 17 | 17180991840016 |
| 18 | 106056375378580 |
| 19 | 654674355426025 |
| 20 | 4041262228505645 |
[1,13,169,936,5184,33408,215296,1323792,8139609, 50261301,310358689,1916465345,11834176225, 73043905820,450847788304,2783165854192, 17180991840016,106056375378580,654674355426025, 4041262228505645] |