n | a(n) |
---|---|
0 | 1 |
1 | 0 |
2 | 6 |
3 | 18 |
4 | 138 |
5 | 762 |
6 | 4698 |
7 | 27930 |
8 | 168090 |
9 | 1007514 |
10 | 6047130 |
11 | 36278682 |
12 | 217680282 |
13 | 1306065306 |
14 | 7836424602 |
15 | 47018482074 |
16 | 282111023514 |
17 | 1692665878938 |
18 | 10155995797914 |
19 | 60935973738906 |
20 | 365615844530586 |
21 | 2193695062989210 |
[1,0,6,18,138,762,4698,27930,168090,1007514, 6047130,36278682,217680282,1306065306,7836424602, 47018482074,282111023514,1692665878938, 10155995797914,60935973738906,365615844530586, 2193695062989210] |