The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 9 |
| 3 | 40 |
| 4 | 282 |
| 5 | 1455 |
| 6 | 7278 |
| 7 | 29849 |
| 8 | 107399 |
| 9 | 330369 |
| 10 | 890152 |
| 11 | 2096153 |
| 12 | 4364470 |
[1,1,9,40,282,1455,7278,29849,107399,330369, 890152,2096153,4364470] |