n | a(n) |
---|---|
1 | 1 |
2 | 6 |
3 | 24 |
4 | 80 |
5 | 273 |
6 | 960 |
7 | 3336 |
8 | 11480 |
9 | 39648 |
10 | 136952 |
11 | 472416 |
12 | 1630164 |
13 | 5625480 |
14 | 19412736 |
15 | 66992016 |
16 | 231184800 |
17 | 797806152 |
18 | 2753187210 |
19 | 9501109380 |
20 | 32787848746 |
[1,6,24,80,273,960,3336,11480,39648,136952,472416, 1630164,5625480,19412736,66992016,231184800, 797806152,2753187210,9501109380,32787848746] |