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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 9 |
| 3 | 33 |
| 4 | 88 |
| 5 | 252 |
| 6 | 737 |
| 7 | 2222 |
| 8 | 6666 |
| 9 | 19691 |
| 10 | 59095 |
| 11 | 177771 |
| 12 | 532235 |
| 13 | 1594951 |
| 14 | 4783874 |
| 15 | 14355341 |
| 16 | 43055034 |
| 17 | 129141921 |
| 18 | 387424783 |
| 19 | 1162332611 |
| 20 | 3486886843 |
| 21 | 10460406401 |
| 22 | 31381118313 |
| 23 | 94143234149 |
| 24 | 282429924282 |
| 25 | 847288882748 |
[1,3,9,33,88,252,737,2222,6666,19691,59095,177771, 532235,1594951,4783874,14355341,43055034, 129141921,387424783,1162332611,3486886843, 10460406401,31381118313,94143234149,282429924282, 847288882748] |