The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 2 |
| 4 | 9 |
| 5 | 24 |
| 6 | 185 |
| 7 | 720 |
| 8 | 7217 |
| 9 | 35840 |
| 10 | 451089 |
| 11 | 2741760 |
| 12 | 41375609 |
| 13 | 297133056 |
| 14 | 5232134921 |
| 15 | 43356465152 |
| 16 | 872492313825 |
| 17 | 8193895956480 |
| 18 | 185503858236065 |
| 19 | 1947095049830400 |
| 20 | 48978641359097705 |
| 21 | 568206904265277440 |
| 22 | 15722400263686662105 |
| 23 | 199768581446090883072 |
[0,1,2,9,24,185,720,7217,35840,451089,2741760, 41375609,297133056,5232134921,43356465152, 872492313825,8193895956480,185503858236065, 1947095049830400,48978641359097705, 568206904265277440,15722400263686662105, 199768581446090883072] |