n | a(n) |
---|---|
0 | 1 |
1 | 1 |
2 | 4 |
3 | 15 |
4 | 82 |
5 | 475 |
6 | 3456 |
7 | 26719 |
8 | 239996 |
9 | 2313609 |
10 | 24846640 |
11 | 285861301 |
12 | 3586817928 |
13 | 47988744115 |
14 | 690525294018 |
15 | 10547453864445 |
16 | 171595180564816 |
17 | 2949836193259105 |
18 | 53630566660122696 |
19 | 1025856767305899229 |
20 | 20638503314068334480 |
[1,1,4,15,82,475,3456,26719,239996,2313609, 24846640,285861301,3586817928,47988744115, 690525294018,10547453864445,171595180564816, 2949836193259105,53630566660122696, 1025856767305899229,20638503314068334480] |