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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 1 |
| 3 | 1 |
| 4 | 18 |
| 5 | 2 |
| 6 | 861 |
| 7 | 132 |
| 8 | 106024 |
| 9 | 40910 |
| 10 | 72980055 |
| 11 | 6838271 |
| 12 | 228282942581 |
| 13 | 27620223647 |
| 14 | 2050169324675668 |
| 15 | 352809815149813 |
| 16 | 87174966874755673105 |
| 17 | 6798293425492905407 |
| 18 | 18318448554980083512011863 |
| 19 | 1187839217207171380193247 |
| 20 | 11258918803635775614062752424535 |
[1,0,1,1,18,2,861,132,106024,40910,72980055, 6838271,228282942581,27620223647,2050169324675668, 352809815149813,87174966874755673105, 6798293425492905407,18318448554980083512011863, 1187839217207171380193247, 11258918803635775614062752424535] |