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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 18 |
| 2 | 99 |
| 3 | 756 |
| 4 | 6597 |
| 5 | 59094 |
| 6 | 531495 |
| 7 | 4783032 |
| 8 | 43046793 |
| 9 | 387420570 |
| 10 | 3486784491 |
| 11 | 31381059708 |
| 12 | 282429536589 |
| 13 | 2541865828446 |
| 14 | 22876792455087 |
| 15 | 205891132094784 |
| 16 | 1853020188851985 |
| 17 | 16677181699666722 |
| 18 | 150094635296999283 |
| 19 | 1350851717672992260 |
| 20 | 12157665459056928981 |
[1,18,99,756,6597,59094,531495,4783032,43046793, 387420570,3486784491,31381059708,282429536589, 2541865828446,22876792455087,205891132094784, 1853020188851985,16677181699666722, 150094635296999283,1350851717672992260, 12157665459056928981] |