| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 5 |
| 3 | 27 |
| 4 | 175 |
| 5 | 1165 |
| 6 | 8221 |
| 7 | 60007 |
| 8 | 449693 |
| 9 | 3437315 |
| 10 | 26700429 |
| 11 | 210147859 |
| 12 | 1672294243 |
| 13 | 13432357463 |
| 14 | 108761156653 |
| 15 | 886785526897 |
| 16 | 7274670122017 |
| 17 | 59999774031797 |
| 18 | 497244626964801 |
| 19 | 4138638973241695 |
| 20 | 34580160863858515 |
| 21 | 289947745327853737 |
[1,5,27,175,1165,8221,60007,449693,3437315, 26700429,210147859,1672294243,13432357463, 108761156653,886785526897,7274670122017, 59999774031797,497244626964801,4138638973241695, 34580160863858515,289947745327853737] |