n | a(n) |
---|---|
1 | 1 |
2 | 0 |
3 | 0 |
4 | 1 |
5 | 4 |
6 | 12 |
7 | 36 |
8 | 116 |
9 | 392 |
10 | 1350 |
11 | 4696 |
12 | 16500 |
13 | 58572 |
14 | 209824 |
15 | 757440 |
16 | 2752185 |
17 | 10057636 |
18 | 36943044 |
19 | 136319052 |
20 | 505086728 |
21 | 1878395920 |
22 | 7009239644 |
23 | 26235435248 |
24 | 98475145476 |
25 | 370584275964 |
26 | 1397918543552 |
27 | 5284861554816 |
[1,0,0,1,4,12,36,116,392,1350,4696,16500,58572, 209824,757440,2752185,10057636,36943044,136319052, 505086728,1878395920,7009239644,26235435248, 98475145476,370584275964,1397918543552, 5284861554816] |