| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 11 |
| 3 | 71 |
| 4 | 481 |
| 5 | 3241 |
| 6 | 21851 |
| 7 | 147311 |
| 8 | 993121 |
| 9 | 6695281 |
| 10 | 45137291 |
| 11 | 304300151 |
| 12 | 2051487361 |
| 13 | 13830424921 |
| 14 | 93239986331 |
| 15 | 628592042591 |
| 16 | 4237752187201 |
| 17 | 28569473336161 |
| 18 | 192605600952971 |
| 19 | 1298480972398631 |
| 20 | 8753913839156641 |
[1,1,11,71,481,3241,21851,147311,993121,6695281, 45137291,304300151,2051487361,13830424921, 93239986331,628592042591,4237752187201, 28569473336161,192605600952971,1298480972398631, 8753913839156641] |