n | a(n) |
---|---|
1 | 0 |
2 | 0 |
3 | 0 |
4 | 1 |
5 | 4 |
6 | 18 |
7 | 79 |
8 | 326 |
9 | 1278 |
10 | 4875 |
11 | 17978 |
12 | 64720 |
13 | 227842 |
14 | 787546 |
15 | 2678207 |
16 | 8982754 |
17 | 29761361 |
18 | 97558039 |
19 | 316778169 |
20 | 1019996738 |
21 | 3259673935 |
22 | 10347077497 |
23 | 32644696187 |
24 | 102425388286 |
25 | 319754805262 |
[0,0,0,1,4,18,79,326,1278,4875,17978,64720,227842, 787546,2678207,8982754,29761361,97558039, 316778169,1019996738,3259673935,10347077497, 32644696187,102425388286,319754805262] |