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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 6 |
| 2 | 63 |
| 3 | 866 |
| 4 | 13899 |
| 5 | 246366 |
| 6 | 4676768 |
| 7 | 93322596 |
| 8 | 1934035965 |
| 9 | 41286407510 |
| 10 | 902562584556 |
| 11 | 20119266633060 |
| 12 | 455832458083577 |
| 13 | 10470568749165246 |
| 14 | 243361203186769659 |
| 15 | 5714294570067499930 |
| 16 | 135377464019074334826 |
| 17 | 3232534121305720233264 |
| 18 | 77726654423445817800164 |
[1,6,63,866,13899,246366,4676768,93322596, 1934035965,41286407510,902562584556, 20119266633060,455832458083577,10470568749165246, 243361203186769659,5714294570067499930, 135377464019074334826,3232534121305720233264, 77726654423445817800164] |