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| n | a(n) |
|---|---|
| 0 | 2 |
| 1 | 1 |
| 2 | 2 |
| 3 | 3 |
| 4 | 7 |
| 5 | 17 |
| 6 | 45 |
| 7 | 128 |
| 8 | 391 |
| 9 | 1287 |
| 10 | 4524 |
| 11 | 16889 |
| 12 | 66657 |
| 13 | 276982 |
| 14 | 1207598 |
| 15 | 5507362 |
| 16 | 26203307 |
| 17 | 129757596 |
| 18 | 667358910 |
| 19 | 3558097578 |
| 20 | 19632277761 |
| 21 | 111930731957 |
| 22 | 658482495614 |
| 23 | 3992062349412 |
| 24 | 24911272290567 |
| 25 | 159833355923362 |
[2,1,2,3,7,17,45,128,391,1287,4524,16889,66657, 276982,1207598,5507362,26203307,129757596, 667358910,3558097578,19632277761,111930731957, 658482495614,3992062349412,24911272290567, 159833355923362] |