| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 6 |
| 2 | 54 |
| 3 | 540 |
| 4 | 5670 |
| 5 | 61236 |
| 6 | 673596 |
| 7 | 7505784 |
| 8 | 84440070 |
| 9 | 956987460 |
| 10 | 10909657044 |
| 11 | 124965162504 |
| 12 | 1437099368796 |
| 13 | 16581915793800 |
| 14 | 191876454185400 |
| 15 | 2225766868550640 |
| 16 | 25874539846901190 |
| 17 | 301362287628613860 |
[1,6,54,540,5670,61236,673596,7505784,84440070, 956987460,10909657044,124965162504,1437099368796, 16581915793800,191876454185400,2225766868550640, 25874539846901190,301362287628613860] |