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| n | a(n) |
|---|---|
| 3 | 1 |
| 4 | 9 |
| 5 | 57 |
| 6 | 316 |
| 7 | 1647 |
| 8 | 8330 |
| 9 | 41558 |
| 10 | 206418 |
| 11 | 1026392 |
| 12 | 5126109 |
| 13 | 25763881 |
| 14 | 130446758 |
| 15 | 665644541 |
| 16 | 3423360416 |
| 17 | 17740450004 |
| 18 | 92599616864 |
| 19 | 486607242642 |
| 20 | 2573051443194 |
| 21 | 13683364565774 |
| 22 | 73146530405912 |
| 23 | 392867752273562 |
| 24 | 2119154966713452 |
[1,9,57,316,1647,8330,41558,206418,1026392, 5126109,25763881,130446758,665644541,3423360416, 17740450004,92599616864,486607242642, 2573051443194,13683364565774,73146530405912, 392867752273562,2119154966713452] |