The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 4 |
| 3 | 48 |
| 4 | 1083 |
| 5 | 58754 |
| 6 | 6986232 |
| 7 | 1856160689 |
| 8 | 1127146150406 |
| 9 | 1548159743720858 |
[1,4,48,1083,58754,6986232,1856160689, 1127146150406,1548159743720858] |