n | a(n) |
---|---|
0 | 0 |
1 | 0 |
2 | 0 |
3 | 0 |
4 | 24 |
5 | 180 |
6 | 900 |
7 | 3780 |
8 | 14448 |
9 | 52164 |
10 | 181500 |
11 | 615780 |
12 | 2052072 |
13 | 6749028 |
14 | 21976500 |
15 | 71007300 |
16 | 228009696 |
17 | 728451972 |
18 | 2317445100 |
19 | 7346047140 |
20 | 23213772120 |
21 | 73156412196 |
22 | 229989358500 |
23 | 721474964100 |
24 | 2258832312144 |
25 | 7059480120900 |
26 | 22026886599900 |
[0,0,0,0,24,180,900,3780,14448,52164,181500, 615780,2052072,6749028,21976500,71007300, 228009696,728451972,2317445100,7346047140, 23213772120,73156412196,229989358500,721474964100, 2258832312144,7059480120900,22026886599900] |