The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 12 |
| 4 | 2520 |
| 5 | 48348686786400 |
| 6 | 10543141534556403817127800577537146514577188497111149855093902265479066128013109211427715400552367011213513440000 |
[1,2,12,2520,48348686786400, 10543141534556403817127800577537146514577188497111\ 14985509390226547906612801310921142771540055236701\ 1213513440000] |