The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 1 |
| 5 | 3 |
| 6 | 28 |
| 7 | 199 |
| 8 | 1603 |
| 9 | 12234 |
| 10 | 93270 |
| 11 | 697641 |
| 12 | 5167477 |
| 13 | 37913465 |
[0,0,0,1,3,28,199,1603,12234,93270,697641,5167477, 37913465] |