n | a(n) |
---|---|
1 | 0 |
2 | 0 |
3 | 1 |
4 | 2 |
5 | 7 |
6 | 14 |
7 | 52 |
8 | 104 |
9 | 333 |
10 | 870 |
11 | 2571 |
12 | 4590 |
13 | 20440 |
14 | 56736 |
15 | 133782 |
16 | 327558 |
17 | 1265391 |
18 | 2612694 |
19 | 10188836 |
20 | 20769420 |
21 | 76562106 |
[0,0,1,2,7,14,52,104,333,870,2571,4590,20440, 56736,133782,327558,1265391,2612694,10188836, 20769420,76562106] |