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| n | a(n) |
|---|---|
| 1 | 8 |
| 2 | 57 |
| 3 | 378 |
| 4 | 2521 |
| 5 | 16818 |
| 6 | 112276 |
| 7 | 749447 |
| 8 | 5002276 |
| 9 | 33388996 |
| 10 | 222863968 |
| 11 | 1487564143 |
| 12 | 9929138252 |
| 13 | 66274651117 |
| 14 | 442367629539 |
| 15 | 2952699342837 |
| 16 | 19708570048557 |
| 17 | 131550045689409 |
| 18 | 878065454645686 |
| 19 | 5860879322317997 |
| 20 | 39119983879518589 |
[8,57,378,2521,16818,112276,749447,5002276, 33388996,222863968,1487564143,9929138252, 66274651117,442367629539,2952699342837, 19708570048557,131550045689409,878065454645686, 5860879322317997,39119983879518589] |