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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 5 |
| 3 | 15 |
| 4 | 44 |
| 5 | 126 |
| 6 | 357 |
| 7 | 1003 |
| 8 | 2783 |
| 9 | 7618 |
| 10 | 20627 |
| 11 | 55421 |
| 12 | 148021 |
| 13 | 393140 |
| 14 | 1038123 |
| 15 | 2724992 |
| 16 | 7112022 |
| 17 | 18465708 |
| 18 | 47726767 |
| 19 | 122861732 |
| 20 | 315123476 |
| 21 | 805428727 |
| 22 | 2051556778 |
| 23 | 5207982062 |
| 24 | 13177117709 |
| 25 | 33235023381 |
| 26 | 83574705456 |
| 27 | 209576713721 |
| 28 | 524181331710 |
| 29 | 1307849984089 |
| 30 | 3255539133109 |
[1,2,5,15,44,126,357,1003,2783,7618,20627,55421, 148021,393140,1038123,2724992,7112022,18465708, 47726767,122861732,315123476,805428727,2051556778, 5207982062,13177117709,33235023381,83574705456, 209576713721,524181331710,1307849984089, 3255539133109] |