n | a(n) |
---|---|
0 | 0 |
1 | 0 |
2 | 3 |
3 | 18 |
4 | 60 |
5 | 210 |
6 | 798 |
7 | 2462 |
8 | 7891 |
9 | 25148 |
10 | 84173 |
11 | 257558 |
12 | 810924 |
13 | 2515962 |
14 | 7706020 |
15 | 24261554 |
16 | 73746402 |
17 | 224417982 |
18 | 683672754 |
19 | 2057559942 |
20 | 6177146990 |
21 | 18671429714 |
22 | 55589344618 |
23 | 165403412230 |
24 | 491940143015 |
25 | 1452537550800 |
26 | 4280665171599 |
27 | 12578264746522 |
[0,0,3,18,60,210,798,2462,7891,25148,84173,257558, 810924,2515962,7706020,24261554,73746402, 224417982,683672754,2057559942,6177146990, 18671429714,55589344618,165403412230,491940143015, 1452537550800,4280665171599,12578264746522] |