The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 10 |
| 4 | 55 |
| 5 | 412 |
| 6 | 3736 |
| 7 | 40518 |
| 8 | 505486 |
| 9 | 7145031 |
| 10 | 112844566 |
| 11 | 1970286922 |
| 12 | 37676184205 |
[1,1,2,10,55,412,3736,40518,505486,7145031, 112844566,1970286922,37676184205] |