n | a(n) |
---|---|
4 | 1 |
5 | 0 |
6 | 3 |
7 | 1 |
8 | 6 |
9 | 9 |
10 | 30 |
11 | 51 |
12 | 198 |
13 | 470 |
14 | 1623 |
15 | 4830 |
16 | 16070 |
17 | 51948 |
18 | 175047 |
19 | 588120 |
20 | 2015226 |
21 | 6933048 |
22 | 24123941 |
23 | 84428820 |
24 | 297753519 |
[1,0,3,1,6,9,30,51,198,470,1623,4830,16070,51948, 175047,588120,2015226,6933048,24123941,84428820, 297753519] |