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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 3 |
| 3 | 12 |
| 4 | 54 |
| 5 | 260 |
| 6 | 1310 |
| 7 | 6824 |
| 8 | 36478 |
| 9 | 199094 |
| 10 | 1105478 |
| 11 | 6227712 |
| 12 | 35520498 |
| 13 | 204773400 |
| 14 | 1191572004 |
| 15 | 6990859416 |
| 16 | 41313818217 |
| 17 | 245735825082 |
| 18 | 1470125583756 |
| 19 | 8840948601024 |
| 20 | 53417237877396 |
| 21 | 324123222435804 |
| 22 | 1974317194619712 |
[1,3,12,54,260,1310,6824,36478,199094,1105478, 6227712,35520498,204773400,1191572004,6990859416, 41313818217,245735825082,1470125583756, 8840948601024,53417237877396,324123222435804, 1974317194619712] |