n | a(n) |
---|---|
1 | 0 |
2 | 0 |
3 | 2 |
4 | 12 |
5 | 50 |
6 | 180 |
7 | 602 |
8 | 1932 |
9 | 6050 |
10 | 18660 |
11 | 57002 |
12 | 173052 |
13 | 523250 |
14 | 1577940 |
15 | 4750202 |
16 | 14283372 |
17 | 42915650 |
18 | 128878020 |
19 | 386896202 |
20 | 1161212892 |
21 | 3484687250 |
22 | 10456158900 |
23 | 31372671002 |
24 | 94126401612 |
25 | 282395982050 |
26 | 847221500580 |
27 | 2541731610602 |
28 | 7625329049532 |
[0,0,2,12,50,180,602,1932,6050,18660,57002,173052, 523250,1577940,4750202,14283372,42915650, 128878020,386896202,1161212892,3484687250, 10456158900,31372671002,94126401612,282395982050, 847221500580,2541731610602,7625329049532] |