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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 4 |
| 3 | 9 |
| 4 | 20 |
| 5 | 44 |
| 6 | 97 |
| 7 | 212 |
| 8 | 455 |
| 9 | 961 |
| 10 | 2014 |
| 11 | 4219 |
| 12 | 8863 |
| 13 | 18662 |
| 14 | 39298 |
| 15 | 82584 |
| 16 | 173008 |
| 17 | 361321 |
| 18 | 752823 |
| 19 | 1566271 |
| 20 | 3256418 |
| 21 | 6768409 |
| 22 | 14064705 |
| 23 | 29213846 |
| 24 | 60634364 |
| 25 | 125706899 |
| 26 | 260227836 |
| 27 | 537737396 |
| 28 | 1108954613 |
[1,2,4,9,20,44,97,212,455,961,2014,4219,8863, 18662,39298,82584,173008,361321,752823,1566271, 3256418,6768409,14064705,29213846,60634364, 125706899,260227836,537737396,1108954613] |