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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 9 |
| 4 | 34 |
| 5 | 120 |
| 6 | 483 |
| 7 | 1886 |
| 8 | 7877 |
| 9 | 32410 |
| 10 | 139157 |
| 11 | 590465 |
| 12 | 2582112 |
| 13 | 11196190 |
| 14 | 49611062 |
| 15 | 218515018 |
| 16 | 978137394 |
| 17 | 4358768473 |
| 18 | 19667296795 |
| 19 | 88439181398 |
| 20 | 401608599218 |
| 21 | 1819068892941 |
| 22 | 8304078080515 |
| 23 | 37835168368298 |
| 24 | 173480557890280 |
| 25 | 794279796478468 |
| 26 | 3655550464599447 |
| 27 | 16805784722604018 |
[1,1,3,9,34,120,483,1886,7877,32410,139157,590465, 2582112,11196190,49611062,218515018,978137394, 4358768473,19667296795,88439181398,401608599218, 1819068892941,8304078080515,37835168368298, 173480557890280,794279796478468,3655550464599447, 16805784722604018] |