The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 2 |
| 3 | 3 |
| 4 | 16 |
| 5 | 30 |
| 6 | 252 |
| 7 | 399 |
| 8 | 4672 |
| 9 | 8100 |
| 10 | 111200 |
| 11 | 193006 |
| 12 | 3279888 |
| 13 | 5631093 |
| 14 | 114137072 |
| 15 | 196030350 |
| 16 | 4600308224 |
| 17 | 7873377297 |
| 18 | 210745840824 |
| 19 | 359490499457 |
| 20 | 10808589776800 |
| 21 | 18389567969010 |
| 22 | 613522956193532 |
| 23 | 1041400845949218 |
| 24 | 38179982045681856 |
| 25 | 64675343605547500 |
| 26 | 2584515863960831060 |
[1,0,2,3,16,30,252,399,4672,8100,111200,193006, 3279888,5631093,114137072,196030350,4600308224, 7873377297,210745840824,359490499457, 10808589776800,18389567969010,613522956193532, 1041400845949218,38179982045681856, 64675343605547500,2584515863960831060] |