n | a(n) |
---|---|
0 | 1 |
1 | 1 |
2 | 2 |
3 | 6 |
4 | 20 |
5 | 90 |
6 | 465 |
7 | 2826 |
8 | 20020 |
9 | 158348 |
10 | 1430189 |
11 | 14217275 |
12 | 157279196 |
13 | 1903617880 |
14 | 25151383277 |
15 | 361228405394 |
16 | 5594555181227 |
17 | 93472423847492 |
18 | 1671138501448565 |
19 | 31988293954710201 |
20 | 651665490924639449 |
[1,1,2,6,20,90,465,2826,20020,158348,1430189, 14217275,157279196,1903617880,25151383277, 361228405394,5594555181227,93472423847492, 1671138501448565,31988293954710201, 651665490924639449] |