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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 21 |
| 5 | 72 |
| 6 | 237 |
| 7 | 761 |
| 8 | 2415 |
| 9 | 7626 |
| 10 | 24034 |
| 11 | 75689 |
| 12 | 238298 |
| 13 | 750179 |
| 14 | 2361533 |
| 15 | 7433917 |
| 16 | 23401274 |
| 17 | 73664906 |
| 18 | 231889749 |
| 19 | 729965584 |
| 20 | 2297858029 |
| 21 | 7233425149 |
| 22 | 22770092131 |
| 23 | 71677951146 |
| 24 | 225634953382 |
| 25 | 710276052265 |
| 26 | 2235877300106 |
[1,2,6,21,72,237,761,2415,7626,24034,75689,238298, 750179,2361533,7433917,23401274,73664906, 231889749,729965584,2297858029,7233425149, 22770092131,71677951146,225634953382,710276052265, 2235877300106] |