| n | a(n) |
|---|---|
| 1 | 3 |
| 2 | 9 |
| 3 | 41 |
| 4 | 172 |
| 5 | 728 |
| 6 | 3084 |
| 7 | 13050 |
| 8 | 55252 |
| 9 | 233875 |
| 10 | 990055 |
| 11 | 4191028 |
| 12 | 17741339 |
| 13 | 75101906 |
| 14 | 317918500 |
| 15 | 1345800258 |
| 16 | 5696989354 |
| 17 | 24116274286 |
| 18 | 102088075950 |
| 19 | 432155280235 |
| 20 | 1829382955772 |
| 21 | 7744072911728 |
| 22 | 32781908823977 |
| 23 | 138771103836595 |
[3,9,41,172,728,3084,13050,55252,233875,990055, 4191028,17741339,75101906,317918500,1345800258, 5696989354,24116274286,102088075950,432155280235, 1829382955772,7744072911728,32781908823977, 138771103836595] |