n | a(n) |
---|---|
1 | 0 |
2 | 0 |
3 | 0 |
4 | 1 |
5 | 4 |
6 | 16 |
7 | 64 |
8 | 236 |
9 | 818 |
10 | 2736 |
11 | 8934 |
12 | 28622 |
13 | 90324 |
14 | 281792 |
15 | 871556 |
16 | 2677750 |
17 | 8184383 |
18 | 24913238 |
19 | 75593383 |
20 | 228793147 |
21 | 691094857 |
22 | 2084237036 |
23 | 6277871658 |
24 | 18890568921 |
25 | 56798001639 |
26 | 170665733660 |
27 | 512554832309 |
28 | 1538718547049 |
[0,0,0,1,4,16,64,236,818,2736,8934,28622,90324, 281792,871556,2677750,8184383,24913238,75593383, 228793147,691094857,2084237036,6277871658, 18890568921,56798001639,170665733660,512554832309, 1538718547049] |