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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 3 |
| 3 | 16 |
| 4 | 84 |
| 5 | 459 |
| 6 | 2552 |
| 7 | 14378 |
| 8 | 81783 |
| 9 | 468622 |
| 10 | 2700926 |
| 11 | 15640800 |
| 12 | 90930523 |
| 13 | 530391615 |
| 14 | 3102491160 |
| 15 | 18192186330 |
| 16 | 106901798100 |
| 17 | 629361849402 |
| 18 | 3711413384462 |
| 19 | 21919199253088 |
| 20 | 129625701167820 |
[1,3,16,84,459,2552,14378,81783,468622,2700926, 15640800,90930523,530391615,3102491160, 18192186330,106901798100,629361849402, 3711413384462,21919199253088,129625701167820] |