The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 5 |
| 4 | 12 |
| 5 | 119 |
| 6 | 135 |
| 7 | 5039 |
| 8 | 20160 |
| 9 | 240219 |
| 10 | 1545075 |
| 11 | 39916799 |
| 12 | 88550154 |
| 13 | 6227020799 |
| 14 | 42798202447 |
| 15 | 698726730520 |
| 16 | 10461394944000 |
| 17 | 355687428095999 |
| 18 | 1375276302469251 |
| 19 | 121645100408831999 |
| 20 | 845066215769150100 |
[1,1,5,12,119,135,5039,20160,240219,1545075, 39916799,88550154,6227020799,42798202447, 698726730520,10461394944000,355687428095999, 1375276302469251,121645100408831999, 845066215769150100] |