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| n | a(n) |
|---|---|
| 0 | 3 |
| 1 | 6 |
| 2 | 19 |
| 3 | 66 |
| 4 | 237 |
| 5 | 866 |
| 6 | 3202 |
| 7 | 11948 |
| 8 | 44917 |
| 9 | 169914 |
| 10 | 646134 |
| 11 | 2467988 |
| 12 | 9462498 |
| 13 | 36398004 |
| 14 | 140399901 |
| 15 | 542894726 |
| 16 | 2103745125 |
| 17 | 8167514346 |
| 18 | 31762430143 |
| 19 | 123704647562 |
| 20 | 482435457922 |
| 21 | 1883712663668 |
| 22 | 7363103647479 |
| 23 | 28809291337986 |
| 24 | 112820819490970 |
| 25 | 442175629583316 |
[3,6,19,66,237,866,3202,11948,44917,169914,646134, 2467988,9462498,36398004,140399901,542894726, 2103745125,8167514346,31762430143,123704647562, 482435457922,1883712663668,7363103647479, 28809291337986,112820819490970,442175629583316] |