n | a(n) |
---|---|
0 | 1 |
1 | 4 |
2 | 20 |
3 | 80 |
4 | 305 |
5 | 1072 |
6 | 3622 |
7 | 11676 |
8 | 36450 |
9 | 110240 |
10 | 324936 |
11 | 935076 |
12 | 2635338 |
13 | 7285560 |
14 | 19795370 |
15 | 52930360 |
16 | 139462956 |
17 | 362471020 |
18 | 930186694 |
19 | 2358867240 |
20 | 5915606398 |
21 | 14680528648 |
22 | 36073675792 |
23 | 87816701332 |
24 | 211891552280 |
25 | 506981067168 |
26 | 1203337174120 |
27 | 2834401172172 |
[1,4,20,80,305,1072,3622,11676,36450,110240, 324936,935076,2635338,7285560,19795370,52930360, 139462956,362471020,930186694,2358867240, 5915606398,14680528648,36073675792,87816701332, 211891552280,506981067168,1203337174120, 2834401172172] |