n | a(n) |
---|---|
1 | 0 |
2 | 8 |
3 | 31 |
4 | 86 |
5 | 221 |
6 | 581 |
7 | 1503 |
8 | 4149 |
9 | 11355 |
10 | 31985 |
11 | 90940 |
12 | 261081 |
13 | 756081 |
14 | 2208197 |
15 | 6483148 |
16 | 19132652 |
17 | 56714624 |
18 | 168806741 |
19 | 504209234 |
[0,8,31,86,221,581,1503,4149,11355,31985,90940, 261081,756081,2208197,6483148,19132652,56714624, 168806741,504209234] |