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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 0 |
| 3 | 3 |
| 4 | 10 |
| 5 | 33 |
| 6 | 106 |
| 7 | 331 |
| 8 | 1009 |
| 9 | 3017 |
| 10 | 8884 |
| 11 | 25841 |
| 12 | 74416 |
| 13 | 212533 |
| 14 | 602785 |
| 15 | 1699503 |
| 16 | 4767166 |
| 17 | 13312641 |
| 18 | 37031254 |
| 19 | 102651967 |
| 20 | 283676689 |
| 21 | 781763381 |
| 22 | 2149017256 |
| 23 | 5894114513 |
| 24 | 16132400860 |
| 25 | 44071485673 |
| 26 | 120188174401 |
| 27 | 327242994651 |
[1,0,3,10,33,106,331,1009,3017,8884,25841,74416, 212533,602785,1699503,4767166,13312641,37031254, 102651967,283676689,781763381,2149017256, 5894114513,16132400860,44071485673,120188174401, 327242994651] |