n | a(n) |
---|---|
1 | 4 |
2 | 20 |
3 | 68 |
4 | 448 |
5 | 2152 |
6 | 10684 |
7 | 55567 |
8 | 280544 |
9 | 1425111 |
10 | 7280350 |
11 | 37165198 |
12 | 189316196 |
13 | 965915209 |
14 | 4926863205 |
15 | 25123365839 |
16 | 128156345456 |
17 | 653685106884 |
18 | 3334114760247 |
19 | 17006120383127 |
20 | 86741818975198 |
21 | 442435364449588 |
[4,20,68,448,2152,10684,55567,280544,1425111, 7280350,37165198,189316196,965915209,4926863205, 25123365839,128156345456,653685106884, 3334114760247,17006120383127,86741818975198, 442435364449588] |