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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 7 |
| 2 | 42 |
| 3 | 203 |
| 4 | 889 |
| 5 | 3535 |
| 6 | 13209 |
| 7 | 46551 |
| 8 | 156905 |
| 9 | 507787 |
| 10 | 1588594 |
| 11 | 4819003 |
| 12 | 14231294 |
| 13 | 41007134 |
| 14 | 115589904 |
| 15 | 319284693 |
| 16 | 865781826 |
| 17 | 2307766118 |
| 18 | 6054769679 |
| 19 | 15652436765 |
| 20 | 39909873983 |
| 21 | 100451866962 |
[1,7,42,203,889,3535,13209,46551,156905,507787, 1588594,4819003,14231294,41007134,115589904, 319284693,865781826,2307766118,6054769679, 15652436765,39909873983,100451866962] |