n | a(n) |
---|---|
1 | 1 |
2 | 0 |
3 | 0 |
4 | 2 |
5 | 4 |
6 | 9 |
7 | 32 |
8 | 90 |
9 | 240 |
10 | 654 |
11 | 1804 |
12 | 4950 |
13 | 13664 |
14 | 37944 |
15 | 106272 |
16 | 298890 |
17 | 843796 |
18 | 2390595 |
19 | 6796160 |
20 | 19370696 |
21 | 55345680 |
22 | 158489298 |
23 | 454803100 |
24 | 1307556162 |
25 | 3765741324 |
26 | 10862667648 |
27 | 31381058880 |
28 | 90780903460 |
29 | 262951527460 |
[1,0,0,2,4,9,32,90,240,654,1804,4950,13664,37944, 106272,298890,843796,2390595,6796160,19370696, 55345680,158489298,454803100,1307556162, 3765741324,10862667648,31381058880,90780903460, 262951527460] |