| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 15 |
| 5 | 238 |
| 6 | 2401 |
| 7 | 22084 |
| 8 | 202922 |
| 9 | 1824043 |
| 10 | 16296072 |
| 11 | 145357801 |
| 12 | 1298682892 |
| 13 | 11638466683 |
| 14 | 104682551230 |
| 15 | 945244226939 |
| 16 | 8568535834789 |
| 17 | 77968773245740 |
| 18 | 712064159940996 |
[0,0,1,15,238,2401,22084,202922,1824043,16296072, 145357801,1298682892,11638466683,104682551230, 945244226939,8568535834789,77968773245740, 712064159940996] |