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| n | a(n) |
|---|---|
| 1 | 3 |
| 2 | 9 |
| 3 | 39 |
| 4 | 170 |
| 5 | 790 |
| 6 | 3729 |
| 7 | 17468 |
| 8 | 82769 |
| 9 | 394904 |
| 10 | 1890877 |
| 11 | 9080800 |
| 12 | 43650638 |
| 13 | 210047292 |
| 14 | 1011165147 |
| 15 | 4869719373 |
| 16 | 23456281889 |
| 17 | 113000007399 |
| 18 | 544411868911 |
| 19 | 2623011742357 |
| 20 | 12638188505237 |
| 21 | 60894518951302 |
| 22 | 293410920660702 |
[3,9,39,170,790,3729,17468,82769,394904,1890877, 9080800,43650638,210047292,1011165147,4869719373, 23456281889,113000007399,544411868911, 2623011742357,12638188505237,60894518951302, 293410920660702] |