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| n | a(n) |
|---|---|
| 1 | 18 |
| 2 | 324 |
| 3 | 1278 |
| 4 | 10098 |
| 5 | 55404 |
| 6 | 365094 |
| 7 | 2187162 |
| 8 | 13759164 |
| 9 | 84389022 |
| 10 | 524422458 |
| 11 | 3236767200 |
| 12 | 20048681286 |
| 13 | 123951850866 |
| 14 | 767084787144 |
| 15 | 4744724741082 |
| 16 | 29355963846786 |
| 17 | 181601409572100 |
| 18 | 1123505977913586 |
| 19 | 6950462612268942 |
[18,324,1278,10098,55404,365094,2187162,13759164, 84389022,524422458,3236767200,20048681286, 123951850866,767084787144,4744724741082, 29355963846786,181601409572100,1123505977913586, 6950462612268942] |