| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 720 |
| 2 | 202410 |
| 3 | 20933840 |
| 4 | 1047649905 |
| 5 | 30767936616 |
| 6 | 602351808741 |
| 7 | 8575979362560 |
| 8 | 94459713879600 |
| 9 | 842286559093240 |
| 10 | 6292583664553881 |
| 11 | 40447642842118656 |
| 12 | 228438173705550566 |
| 13 | 1152877640765297760 |
| 14 | 5271278793334883190 |
| 15 | 22085628572718605376 |
| 16 | 85604721304213863531 |
[1,720,202410,20933840,1047649905,30767936616, 602351808741,8575979362560,94459713879600, 842286559093240,6292583664553881, 40447642842118656,228438173705550566, 1152877640765297760,5271278793334883190, 22085628572718605376,85604721304213863531] |