n | a(n) |
---|---|
1 | 0 |
2 | 4 |
3 | 36 |
4 | 304 |
5 | 2212 |
6 | 15428 |
7 | 103648 |
8 | 680052 |
9 | 4380964 |
10 | 27829504 |
11 | 174806900 |
12 | 1087994628 |
13 | 6720111376 |
14 | 41240210276 |
15 | 251687871332 |
16 | 1528700226512 |
17 | 9246173840644 |
18 | 55718099241732 |
19 | 334660112687936 |
20 | 2004174865390100 |
[0,4,36,304,2212,15428,103648,680052,4380964, 27829504,174806900,1087994628,6720111376, 41240210276,251687871332,1528700226512, 9246173840644,55718099241732,334660112687936, 2004174865390100] |