The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 18 |
| 4 | 384 |
| 5 | 15000 |
| 6 | 933120 |
| 7 | 84707280 |
| 8 | 10569646080 |
| 9 | 1735643790720 |
| 10 | 362880000000000 |
| 11 | 94121726392108800 |
| 12 | 29658516531078758400 |
| 13 | 11159820050604594969600 |
| 14 | 4942478402320838374195200 |
| 15 | 2544989406021562500000000000 |
| 16 | 1507645899890367707813511168000 |
[1,2,18,384,15000,933120,84707280,10569646080, 1735643790720,362880000000000,94121726392108800, 29658516531078758400,11159820050604594969600, 4942478402320838374195200, 2544989406021562500000000000, 1507645899890367707813511168000] |