The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 3 |
| 4 | 15 |
| 5 | 98 |
| 6 | 596 |
| 7 | 3626 |
| 8 | 22704 |
| 9 | 146834 |
| 10 | 983476 |
| 11 | 6846451 |
| 12 | 49364315 |
| 13 | 367660050 |
[0,0,3,15,98,596,3626,22704,146834,983476,6846451, 49364315,367660050] |