The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 1 |
| 5 | 12 |
| 6 | 120 |
| 7 | 896 |
| 8 | 5544 |
| 9 | 30384 |
| 10 | 153400 |
| 11 | 731040 |
| 12 | 3341256 |
| 13 | 14806544 |
| 14 | 64107096 |
| 15 | 272697216 |
| 16 | 1144354792 |
| 17 | 4752083952 |
| 18 | 19573444728 |
| 19 | 80110516064 |
| 20 | 326251853832 |
| 21 | 1323504508368 |
| 22 | 5352686795416 |
| 23 | 21596226671424 |
| 24 | 86969629500456 |
| 25 | 349717233298352 |
| 26 | 1404638031773880 |
[0,0,0,0,1,12,120,896,5544,30384,153400,731040, 3341256,14806544,64107096,272697216,1144354792, 4752083952,19573444728,80110516064,326251853832, 1323504508368,5352686795416,21596226671424, 86969629500456,349717233298352,1404638031773880] |