n | a(n) |
---|---|
0 | 1 |
1 | 1 |
2 | 4 |
3 | 18 |
4 | 120 |
5 | 960 |
6 | 9360 |
7 | 105840 |
8 | 1370880 |
9 | 19958400 |
10 | 322963200 |
11 | 5748019200 |
12 | 111607372800 |
13 | 2347586841600 |
14 | 53178757632000 |
15 | 1290674601216000 |
16 | 33413695451136000 |
17 | 919096314200064000 |
18 | 26768324463648768000 |
[1,1,4,18,120,960,9360,105840,1370880,19958400, 322963200,5748019200,111607372800,2347586841600, 53178757632000,1290674601216000,33413695451136000, 919096314200064000,26768324463648768000] |