The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 0 |
| 6 | 0 |
| 7 | 1 |
| 8 | 7 |
| 9 | 34 |
| 10 | 143 |
| 11 | 555 |
| 12 | 2050 |
| 13 | 7343 |
| 14 | 25809 |
| 15 | 89642 |
| 16 | 308986 |
| 17 | 1059786 |
| 18 | 3623524 |
| 19 | 12365973 |
| 20 | 42160774 |
| 21 | 143701920 |
| 22 | 489891138 |
| 23 | 1670965268 |
[0,0,0,0,0,0,0,1,7,34,143,555,2050,7343,25809, 89642,308986,1059786,3623524,12365973,42160774, 143701920,489891138,1670965268] |