n | a(n) |
---|---|
1 | 0 |
2 | 4 |
3 | 12 |
4 | 24 |
5 | 72 |
6 | 252 |
7 | 756 |
8 | 2160 |
9 | 6480 |
10 | 19764 |
11 | 59292 |
12 | 176904 |
13 | 530712 |
14 | 1595052 |
15 | 4785156 |
16 | 14346720 |
17 | 43040160 |
18 | 129146724 |
19 | 387440172 |
20 | 1162241784 |
21 | 3486725352 |
22 | 10460412252 |
23 | 31381236756 |
24 | 94143001680 |
25 | 282429005040 |
26 | 847289140884 |
27 | 2541867422652 |
28 | 7625595890664 |
29 | 22876787671992 |
[0,4,12,24,72,252,756,2160,6480,19764,59292, 176904,530712,1595052,4785156,14346720,43040160, 129146724,387440172,1162241784,3486725352, 10460412252,31381236756,94143001680,282429005040, 847289140884,2541867422652,7625595890664, 22876787671992] |