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| n | a(n) |
|---|---|
| 1 | 81 |
| 2 | 561 |
| 3 | 3906 |
| 4 | 27225 |
| 5 | 189801 |
| 6 | 1323270 |
| 7 | 9225765 |
| 8 | 64321641 |
| 9 | 448447914 |
| 10 | 3126561201 |
| 11 | 21798261945 |
| 12 | 151976626974 |
| 13 | 1059575080797 |
| 14 | 7387315894233 |
| 15 | 51504076597986 |
| 16 | 359084401453161 |
| 17 | 2503522359474057 |
| 18 | 17454459673057014 |
| 19 | 121691808074121237 |
[81,561,3906,27225,189801,1323270,9225765, 64321641,448447914,3126561201,21798261945, 151976626974,1059575080797,7387315894233, 51504076597986,359084401453161,2503522359474057, 17454459673057014,121691808074121237] |