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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 27 |
| 2 | 378 |
| 3 | 3681 |
| 4 | 28134 |
| 5 | 180144 |
| 6 | 1005957 |
| 7 | 5032422 |
| 8 | 22986801 |
| 9 | 97229361 |
| 10 | 384953553 |
| 11 | 1438738443 |
| 12 | 5110502256 |
| 13 | 17348445108 |
| 14 | 56541857409 |
| 15 | 177611637141 |
| 16 | 539501563962 |
| 17 | 1589134470966 |
| 18 | 4550281700055 |
| 19 | 12692702415312 |
| 20 | 34556103662778 |
| 21 | 91975719684573 |
| 22 | 239686155975618 |
[1,27,378,3681,28134,180144,1005957,5032422, 22986801,97229361,384953553,1438738443,5110502256, 17348445108,56541857409,177611637141,539501563962, 1589134470966,4550281700055,12692702415312, 34556103662778,91975719684573,239686155975618] |