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 | 4 |
| 5 | 30 |
| 6 | 200 |
| 7 | 1435 |
| 8 | 11536 |
| 9 | 103908 |
| 10 | 1039200 |
| 11 | 11431365 |
| 12 | 137176600 |
| 13 | 1783296086 |
| 14 | 24966145568 |
| 15 | 374492183975 |
| 16 | 5991874944160 |
| 17 | 101861874051400 |
| 18 | 1833513732926016 |
| 19 | 34836760925595273 |
| 20 | 696735218511906600 |
| 21 | 14631439588750039930 |
| 22 | 321891670952500880000 |
| 23 | 7403508431907520241771 |
[0,0,0,0,4,30,200,1435,11536,103908,1039200, 11431365,137176600,1783296086,24966145568, 374492183975,5991874944160,101861874051400, 1833513732926016,34836760925595273, 696735218511906600,14631439588750039930, 321891670952500880000,7403508431907520241771] |