n | a(n) |
---|---|
0 | 1 |
1 | 1 |
2 | 4 |
3 | 16 |
4 | 78 |
5 | 420 |
6 | 2454 |
7 | 15297 |
8 | 100660 |
9 | 694022 |
10 | 4986128 |
11 | 37171749 |
12 | 286619290 |
13 | 2279866324 |
14 | 18668221560 |
15 | 157080129914 |
16 | 1356186583276 |
17 | 11999018622158 |
18 | 108672944038356 |
19 | 1006528378511868 |
20 | 9525454067974148 |
21 | 92037443236217412 |
[1,1,4,16,78,420,2454,15297,100660,694022,4986128, 37171749,286619290,2279866324,18668221560, 157080129914,1356186583276,11999018622158, 108672944038356,1006528378511868,9525454067974148, 92037443236217412] |