n | a(n) |
---|---|
1 | 1 |
2 | 4 |
3 | 20 |
4 | 220 |
5 | 1540 |
6 | 30800 |
7 | 277200 |
8 | 7207200 |
9 | 129729600 |
10 | 3632428800 |
11 | 47221574400 |
12 | 2597186592000 |
13 | 38957798880000 |
14 | 1402480759680000 |
15 | 49086826588800000 |
16 | 2797949115561600000 |
17 | 53161033195670400000 |
18 | 3827594390088268800000 |
19 | 80379482191853644800000 |
[1,4,20,220,1540,30800,277200,7207200,129729600, 3632428800,47221574400,2597186592000, 38957798880000,1402480759680000,49086826588800000, 2797949115561600000,53161033195670400000, 3827594390088268800000,80379482191853644800000] |