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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 13 |
| 5 | 41 |
| 6 | 133 |
| 7 | 457 |
| 8 | 1626 |
| 9 | 5983 |
| 10 | 22581 |
| 11 | 86273 |
| 12 | 332309 |
| 13 | 1289466 |
| 14 | 5037491 |
| 15 | 19814253 |
| 16 | 78464829 |
| 17 | 312698663 |
| 18 | 1253236364 |
| 19 | 5047142834 |
| 20 | 20408861265 |
| 21 | 82804575274 |
| 22 | 336913925731 |
| 23 | 1374181645807 |
| 24 | 5617148927835 |
| 25 | 23007022273962 |
[1,2,4,13,41,133,457,1626,5983,22581,86273,332309, 1289466,5037491,19814253,78464829,312698663, 1253236364,5047142834,20408861265,82804575274, 336913925731,1374181645807,5617148927835, 23007022273962] |