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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 5 |
| 3 | 20 |
| 4 | 137 |
| 5 | 1478 |
| 6 | 22925 |
| 7 | 481448 |
| 8 | 13138193 |
| 9 | 451749962 |
| 10 | 19104365333 |
| 11 | 974417603132 |
| 12 | 58981977530777 |
| 13 | 4179837144348686 |
| 14 | 342799255549127837 |
| 15 | 32212592211380729168 |
| 16 | 3438255899105307857441 |
| 17 | 413670348773363088131474 |
| 18 | 55722273751954119897519653 |
[1,2,5,20,137,1478,22925,481448,13138193, 451749962,19104365333,974417603132,58981977530777, 4179837144348686,342799255549127837, 32212592211380729168,3438255899105307857441, 413670348773363088131474, 55722273751954119897519653] |