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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 6 |
| 3 | 57 |
| 4 | 796 |
| 5 | 14785 |
| 6 | 344046 |
| 7 | 9640225 |
| 8 | 316255416 |
| 9 | 11896233345 |
| 10 | 504918768250 |
| 11 | 23874754106401 |
| 12 | 1244712973780068 |
| 13 | 70940791877082049 |
| 14 | 4388291507415513894 |
| 15 | 292823509879910802465 |
| 16 | 20966854494419642792176 |
| 17 | 1603540841320336494905089 |
| 18 | 130464295561360336835272050 |
[1,1,6,57,796,14785,344046,9640225,316255416, 11896233345,504918768250,23874754106401, 1244712973780068,70940791877082049, 4388291507415513894,292823509879910802465, 20966854494419642792176,1603540841320336494905089, 130464295561360336835272050] |