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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 10 |
| 3 | 21 |
| 4 | 51 |
| 5 | 97 |
| 6 | 219 |
| 7 | 405 |
| 8 | 896 |
| 9 | 1643 |
| 10 | 3609 |
| 11 | 6599 |
| 12 | 14465 |
| 13 | 26427 |
| 14 | 57893 |
| 15 | 105743 |
| 16 | 231609 |
| 17 | 423011 |
| 18 | 926478 |
| 19 | 1692089 |
| 20 | 3705959 |
| 21 | 6768405 |
| 22 | 14823887 |
| 23 | 27073673 |
| 24 | 59295603 |
| 25 | 108294749 |
| 26 | 237182471 |
[1,3,10,21,51,97,219,405,896,1643,3609,6599,14465, 26427,57893,105743,231609,423011,926478,1692089, 3705959,6768405,14823887,27073673,59295603, 108294749,237182471] |