n | a(n) |
---|---|
0 | 1 |
1 | 4 |
2 | 15 |
3 | 56 |
4 | 212 |
5 | 816 |
6 | 3184 |
7 | 12544 |
8 | 49728 |
9 | 197888 |
10 | 789248 |
11 | 3151872 |
12 | 12596224 |
13 | 50360320 |
14 | 201388032 |
15 | 805437440 |
16 | 3221504000 |
17 | 12885491712 |
18 | 51540852736 |
19 | 206161051648 |
20 | 824639225856 |
21 | 3298546417664 |
22 | 13194163650560 |
23 | 52776608464896 |
[1,4,15,56,212,816,3184,12544,49728,197888,789248, 3151872,12596224,50360320,201388032,805437440, 3221504000,12885491712,51540852736,206161051648, 824639225856,3298546417664,13194163650560, 52776608464896] |