n | a(n) |
---|---|
0 | 0 |
1 | 0 |
2 | 0 |
3 | 0 |
4 | 1 |
5 | 4 |
6 | 20 |
7 | 80 |
8 | 315 |
9 | 1176 |
10 | 4284 |
11 | 15240 |
12 | 53295 |
13 | 183700 |
14 | 625768 |
15 | 2110472 |
16 | 7057505 |
17 | 23427600 |
18 | 77271120 |
19 | 253426752 |
20 | 827009523 |
21 | 2686728060 |
22 | 8693388060 |
23 | 28026897360 |
24 | 90058925649 |
25 | 288516259416 |
26 | 921755412900 |
27 | 2937377079000 |
28 | 9338728806225 |
29 | 29626186593276 |
[0,0,0,0,1,4,20,80,315,1176,4284,15240,53295, 183700,625768,2110472,7057505,23427600,77271120, 253426752,827009523,2686728060,8693388060, 28026897360,90058925649,288516259416,921755412900, 2937377079000,9338728806225,29626186593276] |