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| n | a(n) |
|---|---|
| 1 | 18 |
| 2 | 324 |
| 3 | 1014 |
| 4 | 3513 |
| 5 | 14184 |
| 6 | 45520 |
| 7 | 135686 |
| 8 | 417772 |
| 9 | 1253238 |
| 10 | 3651096 |
| 11 | 10647801 |
| 12 | 30923564 |
| 13 | 88853464 |
| 14 | 254267485 |
| 15 | 725590642 |
| 16 | 2060214105 |
| 17 | 5827339605 |
| 18 | 16437397037 |
| 19 | 46220378910 |
| 20 | 129590864085 |
| 21 | 362487844504 |
| 22 | 1011664530775 |
| 23 | 2817477642474 |
[18,324,1014,3513,14184,45520,135686,417772, 1253238,3651096,10647801,30923564,88853464, 254267485,725590642,2060214105,5827339605, 16437397037,46220378910,129590864085,362487844504, 1011664530775,2817477642474] |