The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 18 |
| 2 | 1200 |
| 3 | 176400 |
| 4 | 45722880 |
| 5 | 18441561600 |
| 6 | 10685567692800 |
| 7 | 8414884558080000 |
| 8 | 8646761377013760000 |
| 9 | 11237331085567082496000 |
| 10 | 18020592759036666839040000 |
| 11 | 34953943088278121445457920000 |
| 12 | 80662945588334126412595200000000 |
| 13 | 218412210097326433146332774400000000 |
[1,18,1200,176400,45722880,18441561600, 10685567692800,8414884558080000, 8646761377013760000,11237331085567082496000, 18020592759036666839040000, 34953943088278121445457920000, 80662945588334126412595200000000, 218412210097326433146332774400000000] |