n | a(n) |
---|---|
1 | 0 |
2 | 0 |
3 | 0 |
4 | 1 |
5 | 9 |
6 | 39 |
7 | 197 |
8 | 721 |
9 | 2717 |
10 | 8211 |
11 | 19836 |
12 | 74497 |
13 | 132611 |
14 | 403534 |
15 | 1127416 |
16 | 2364402 |
17 | 4173316 |
18 | 15604400 |
19 | 21318428 |
20 | 73965916 |
21 | 154211880 |
[0,0,0,1,9,39,197,721,2717,8211,19836,74497, 132611,403534,1127416,2364402,4173316,15604400, 21318428,73965916,154211880] |