| n | a(n) |
|---|---|
| 1 | 6 |
| 2 | 26 |
| 3 | 129 |
| 4 | 647 |
| 5 | 3263 |
| 6 | 16453 |
| 7 | 82971 |
| 8 | 418433 |
| 9 | 2110227 |
| 10 | 10642223 |
| 11 | 53670491 |
| 12 | 270669172 |
| 13 | 1365029469 |
| 14 | 6884069717 |
| 15 | 34717503879 |
| 16 | 175086122783 |
| 17 | 882988319045 |
| 18 | 4453056354096 |
| 19 | 22457500812922 |
| 20 | 113256896535457 |
| 21 | 571173289481198 |
[6,26,129,647,3263,16453,82971,418433,2110227, 10642223,53670491,270669172,1365029469,6884069717, 34717503879,175086122783,882988319045, 4453056354096,22457500812922,113256896535457, 571173289481198] |