n | a(n) |
---|---|
0 | 1 |
1 | 1 |
2 | 2 |
3 | 4 |
4 | 12 |
5 | 40 |
6 | 180 |
7 | 936 |
8 | 5820 |
9 | 41288 |
10 | 331748 |
11 | 2968688 |
12 | 29307780 |
13 | 316273976 |
14 | 3704154568 |
15 | 46788812168 |
16 | 634037127612 |
17 | 9174782661984 |
18 | 141197140912208 |
19 | 2302765704401360 |
20 | 39671953757409256 |
21 | 719926077632193848 |
22 | 13726066030661998220 |
23 | 274313334040504957368 |
[1,1,2,4,12,40,180,936,5820,41288,331748,2968688, 29307780,316273976,3704154568,46788812168, 634037127612,9174782661984,141197140912208, 2302765704401360,39671953757409256, 719926077632193848,13726066030661998220, 274313334040504957368] |