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| n | a(n) |
|---|---|
| 3 | 1 |
| 4 | 9 |
| 5 | 56 |
| 6 | 301 |
| 7 | 1504 |
| 8 | 7217 |
| 9 | 33821 |
| 10 | 156274 |
| 11 | 716116 |
| 12 | 3266558 |
| 13 | 14868789 |
| 14 | 67649170 |
| 15 | 307997855 |
| 16 | 1404343584 |
| 17 | 6416130302 |
| 18 | 29383457373 |
| 19 | 134915391509 |
| 20 | 621163581667 |
| 21 | 2867888163907 |
| 22 | 13278007815855 |
| 23 | 61645847283931 |
| 24 | 286977785803129 |
[1,9,56,301,1504,7217,33821,156274,716116,3266558, 14868789,67649170,307997855,1404343584,6416130302, 29383457373,134915391509,621163581667, 2867888163907,13278007815855,61645847283931, 286977785803129] |