n | a(n) |
---|---|
0 | 0 |
1 | 1 |
2 | 2 |
3 | 7 |
4 | 20 |
5 | 117 |
6 | 518 |
7 | 4555 |
8 | 27432 |
9 | 317577 |
10 | 2405194 |
11 | 34316335 |
12 | 312554428 |
13 | 5287957053 |
14 | 56240197198 |
15 | 1099518892339 |
16 | 13369846932560 |
17 | 296443784525713 |
18 | 4056020122211730 |
19 | 100546719214082775 |
20 | 1528702557462347620 |
[0,1,2,7,20,117,518,4555,27432,317577,2405194, 34316335,312554428,5287957053,56240197198, 1099518892339,13369846932560,296443784525713, 4056020122211730,100546719214082775, 1528702557462347620] |