The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 0 |
| 4 | 0 |
| 5 | 0 |
| 6 | 360 |
| 7 | 2520 |
| 8 | 20160 |
| 9 | 120960 |
| 10 | 1209600 |
| 11 | 13305600 |
| 12 | 179625600 |
| 13 | 2335132800 |
| 14 | 32691859200 |
| 15 | 479480601600 |
| 16 | 7671689625600 |
| 17 | 130418723635200 |
| 18 | 2356429211136000 |
| 19 | 44772155011584000 |
| 20 | 895443100231680000 |
| 21 | 18794168013164544000 |
| 22 | 413471696289619968000 |
[1,1,2,0,0,0,360,2520,20160,120960,1209600, 13305600,179625600,2335132800,32691859200, 479480601600,7671689625600,130418723635200, 2356429211136000,44772155011584000, 895443100231680000,18794168013164544000, 413471696289619968000] |