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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 9 |
| 5 | 21 |
| 6 | 51 |
| 7 | 124 |
| 8 | 305 |
| 9 | 755 |
| 10 | 1879 |
| 11 | 4698 |
| 12 | 11792 |
| 13 | 29694 |
| 14 | 74984 |
| 15 | 189811 |
| 16 | 481498 |
| 17 | 1223713 |
| 18 | 3115200 |
| 19 | 7942134 |
| 20 | 20275362 |
| 21 | 51823246 |
| 22 | 132604193 |
| 23 | 339644739 |
| 24 | 870745187 |
| 25 | 2234208932 |
| 26 | 5737129623 |
| 27 | 14742751524 |
| 28 | 37909928908 |
| 29 | 97543380598 |
[1,1,2,4,9,21,51,124,305,755,1879,4698,11792, 29694,74984,189811,481498,1223713,3115200,7942134, 20275362,51823246,132604193,339644739,870745187, 2234208932,5737129623,14742751524,37909928908, 97543380598] |