n | a(n) |
---|---|
0 | 1 |
1 | 1 |
2 | 2 |
3 | 6 |
4 | 18 |
5 | 90 |
6 | 540 |
7 | 3780 |
8 | 31500 |
9 | 283500 |
10 | 2835000 |
11 | 31185000 |
12 | 372972600 |
13 | 4848643800 |
14 | 67881013200 |
15 | 1018215198000 |
16 | 16294848570000 |
17 | 277012425690000 |
18 | 4986223662420000 |
19 | 94738249585980000 |
20 | 1894745192712372000 |
21 | 39789649046959812000 |
22 | 875372279033115864000 |
[1,1,2,6,18,90,540,3780,31500,283500,2835000, 31185000,372972600,4848643800,67881013200, 1018215198000,16294848570000,277012425690000, 4986223662420000,94738249585980000, 1894745192712372000,39789649046959812000, 875372279033115864000] |