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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 9 |
| 4 | 28 |
| 5 | 88 |
| 6 | 279 |
| 7 | 889 |
| 8 | 2843 |
| 9 | 9115 |
| 10 | 29279 |
| 11 | 94183 |
| 12 | 303294 |
| 13 | 977522 |
| 14 | 3152709 |
| 15 | 10173671 |
| 16 | 32844544 |
| 17 | 106073200 |
| 18 | 342671109 |
| 19 | 1107278239 |
| 20 | 3578704532 |
| 21 | 11568322736 |
| 22 | 37400611581 |
| 23 | 120931966547 |
| 24 | 391065616195 |
| 25 | 1264729338163 |
| 26 | 4090528413309 |
| 27 | 13230930776769 |
| 28 | 42798305388298 |
[1,1,3,9,28,88,279,889,2843,9115,29279,94183, 303294,977522,3152709,10173671,32844544,106073200, 342671109,1107278239,3578704532,11568322736, 37400611581,120931966547,391065616195, 1264729338163,4090528413309,13230930776769, 42798305388298] |