n | a(n) |
---|---|
0 | 1 |
1 | 1 |
2 | 2 |
3 | 6 |
4 | 18 |
5 | 90 |
6 | 540 |
7 | 3060 |
8 | 20700 |
9 | 145980 |
10 | 1459800 |
11 | 13854600 |
12 | 140059800 |
13 | 1514748600 |
14 | 15869034000 |
15 | 285268878000 |
16 | 4109761962000 |
17 | 59488383690000 |
18 | 935767530036000 |
19 | 13364309726748000 |
20 | 240338216104020000 |
21 | 4540941256642020000 |
22 | 79739974380153240000 |
[1,1,2,6,18,90,540,3060,20700,145980,1459800, 13854600,140059800,1514748600,15869034000, 285268878000,4109761962000,59488383690000, 935767530036000,13364309726748000, 240338216104020000,4540941256642020000, 79739974380153240000] |