n | a(n) |
---|---|
0 | 0 |
1 | 1 |
2 | 4 |
3 | 20 |
4 | 124 |
5 | 920 |
6 | 7940 |
7 | 78040 |
8 | 859580 |
9 | 10477880 |
10 | 139931620 |
11 | 2030707640 |
12 | 31805257340 |
13 | 534514790680 |
14 | 9591325648580 |
15 | 182974870484120 |
16 | 3697147584561340 |
17 | 78861451031150840 |
18 | 1770536585183202980 |
19 | 41729280102868841080 |
20 | 1030007496863617367420 |
21 | 26568602827124392999640 |
[0,1,4,20,124,920,7940,78040,859580,10477880, 139931620,2030707640,31805257340,534514790680, 9591325648580,182974870484120,3697147584561340, 78861451031150840,1770536585183202980, 41729280102868841080,1030007496863617367420, 26568602827124392999640] |