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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 4 |
| 3 | 14 |
| 4 | 52 |
| 5 | 248 |
| 6 | 1416 |
| 7 | 9172 |
| 8 | 66366 |
| 9 | 518868 |
| 10 | 4301350 |
| 11 | 37230364 |
| 12 | 333058463 |
| 13 | 3057319072 |
| 14 | 28656583950 |
| 15 | 273298352168 |
| 16 | 2645186193457 |
| 17 | 25931472185976 |
[1,2,4,14,52,248,1416,9172,66366,518868,4301350, 37230364,333058463,3057319072,28656583950, 273298352168,2645186193457,25931472185976] |