The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 1 |
| 6 | 15 |
| 7 | 465 |
| 8 | 19355 |
| 9 | 1024380 |
| 10 | 66462480 |
| 11 | 5188446900 |
| 12 | 480413448900 |
| 13 | 52113339432000 |
| 14 | 6551243302804200 |
| 15 | 945313572845842200 |
| 16 | 155243683741953807000 |
| 17 | 28797215441570535960000 |
| 18 | 5993001571565164940784000 |
| 19 | 1390759438984816084192008000 |
[0,0,0,0,1,15,465,19355,1024380,66462480, 5188446900,480413448900,52113339432000, 6551243302804200,945313572845842200, 155243683741953807000,28797215441570535960000, 5993001571565164940784000, 1390759438984816084192008000] |