n | a(n) |
---|---|
1 | 1 |
2 | 0 |
3 | 2 |
4 | 4 |
5 | 17 |
6 | 28 |
7 | 189 |
8 | 531 |
9 | 1990 |
10 | 5747 |
11 | 23902 |
12 | 76658 |
13 | 291478 |
14 | 982793 |
15 | 3677580 |
16 | 13214719 |
17 | 49161612 |
18 | 177190667 |
19 | 664806798 |
20 | 2443387945 |
[1,0,2,4,17,28,189,531,1990,5747,23902,76658, 291478,982793,3677580,13214719,49161612,177190667, 664806798,2443387945] |