The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 6 |
| 3 | 36 |
| 4 | 336 |
| 5 | 4380 |
| 6 | 73080 |
| 7 | 1481844 |
| 8 | 35320992 |
| 9 | 966875724 |
| 10 | 29874822600 |
| 11 | 1028081942052 |
| 12 | 38985534525168 |
| 13 | 1614899447153148 |
| 14 | 72543518616692760 |
| 15 | 3512306387815898580 |
| 16 | 182320857226312198464 |
| 17 | 10100520471366488756652 |
| 18 | 594804877105749056467560 |
[0,0,6,36,336,4380,73080,1481844,35320992, 966875724,29874822600,1028081942052, 38985534525168,1614899447153148,72543518616692760, 3512306387815898580,182320857226312198464, 10100520471366488756652,594804877105749056467560] |