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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 21 |
| 5 | 71 |
| 6 | 229 |
| 7 | 726 |
| 8 | 2299 |
| 9 | 7296 |
| 10 | 23180 |
| 11 | 73648 |
| 12 | 233935 |
| 13 | 742924 |
| 14 | 2359143 |
| 15 | 7491146 |
| 16 | 23786672 |
| 17 | 75528789 |
| 18 | 239820410 |
| 19 | 761475614 |
| 20 | 2417816525 |
| 21 | 7676955811 |
| 22 | 24375507011 |
| 23 | 77395827653 |
| 24 | 245742882637 |
| 25 | 780268393400 |
| 26 | 2477461176578 |
[1,2,6,21,71,229,726,2299,7296,23180,73648,233935, 742924,2359143,7491146,23786672,75528789, 239820410,761475614,2417816525,7676955811, 24375507011,77395827653,245742882637,780268393400, 2477461176578] |