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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 18 |
| 3 | 189 |
| 4 | 2106 |
| 5 | 22113 |
| 6 | 220158 |
| 7 | 2114829 |
| 8 | 19853586 |
| 9 | 183662073 |
| 10 | 1683014598 |
| 11 | 15327998469 |
| 12 | 139038783066 |
| 13 | 1257874611633 |
| 14 | 11360039237838 |
| 15 | 102475402586109 |
| 16 | 923689049088546 |
| 17 | 8321664384098793 |
| 18 | 74945758272961878 |
| 19 | 674816500839877749 |
[1,3,18,189,2106,22113,220158,2114829,19853586, 183662073,1683014598,15327998469,139038783066, 1257874611633,11360039237838,102475402586109, 923689049088546,8321664384098793, 74945758272961878,674816500839877749] |