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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 4 |
| 3 | 29 |
| 4 | 168 |
| 5 | 1049 |
| 6 | 6380 |
| 7 | 39157 |
| 8 | 239568 |
| 9 | 1467313 |
| 10 | 8983636 |
| 11 | 55009613 |
| 12 | 336825720 |
| 13 | 2062427849 |
| 14 | 12628445756 |
| 15 | 77325345061 |
| 16 | 473471175072 |
| 17 | 2899114186081 |
| 18 | 17751582020260 |
| 19 | 108694812500093 |
| 20 | 665549816263752 |
| 21 | 4075231827556217 |
| 22 | 24953074921653644 |
| 23 | 152790313444845397 |
[1,4,29,168,1049,6380,39157,239568,1467313, 8983636,55009613,336825720,2062427849,12628445756, 77325345061,473471175072,2899114186081, 17751582020260,108694812500093,665549816263752, 4075231827556217,24953074921653644, 152790313444845397] |