n | a(n) |
---|---|
1 | 0 |
2 | 4 |
3 | 18 |
4 | 68 |
5 | 250 |
6 | 922 |
7 | 3430 |
8 | 12868 |
9 | 48618 |
10 | 184754 |
11 | 705430 |
12 | 2704154 |
13 | 10400598 |
14 | 40116598 |
15 | 155117518 |
16 | 601080388 |
17 | 2333606218 |
18 | 9075135298 |
19 | 35345263798 |
20 | 137846528818 |
21 | 538257874438 |
22 | 2104098963718 |
23 | 8233430727598 |
24 | 32247603683098 |
[0,4,18,68,250,922,3430,12868,48618,184754,705430, 2704154,10400598,40116598,155117518,601080388, 2333606218,9075135298,35345263798,137846528818, 538257874438,2104098963718,8233430727598, 32247603683098] |