n | a(n) |
---|---|
1 | 0 |
2 | 5 |
3 | 20 |
4 | 90 |
5 | 300 |
6 | 930 |
7 | 2610 |
8 | 6900 |
9 | 17295 |
10 | 41605 |
11 | 96660 |
12 | 218145 |
13 | 480225 |
14 | 1034765 |
15 | 2188385 |
16 | 4552745 |
17 | 9334760 |
18 | 18892805 |
19 | 37794765 |
20 | 74817520 |
21 | 146702410 |
22 | 285169310 |
23 | 549948760 |
24 | 1052879110 |
25 | 2002263910 |
26 | 3784182685 |
27 | 7110957850 |
28 | 13291250220 |
[0,5,20,90,300,930,2610,6900,17295,41605,96660, 218145,480225,1034765,2188385,4552745,9334760, 18892805,37794765,74817520,146702410,285169310, 549948760,1052879110,2002263910,3784182685, 7110957850,13291250220] |