n | a(n) |
---|---|
0 | 1 |
1 | 6 |
2 | 18 |
3 | 60 |
4 | 210 |
5 | 756 |
6 | 2772 |
7 | 10296 |
8 | 38610 |
9 | 145860 |
10 | 554268 |
11 | 2116296 |
12 | 8112468 |
13 | 31201800 |
14 | 120349800 |
15 | 465352560 |
16 | 1803241170 |
17 | 7000818660 |
18 | 27225405900 |
19 | 106035791400 |
20 | 413539586460 |
21 | 1614773623320 |
[1,6,18,60,210,756,2772,10296,38610,145860,554268, 2116296,8112468,31201800,120349800,465352560, 1803241170,7000818660,27225405900,106035791400, 413539586460,1614773623320] |