n | a(n) |
---|---|
1 | 0 |
2 | 0 |
3 | 0 |
4 | 6 |
5 | 48 |
6 | 260 |
7 | 1200 |
8 | 5106 |
9 | 20720 |
10 | 81876 |
11 | 318000 |
12 | 1223136 |
13 | 4675440 |
14 | 17815020 |
15 | 67769552 |
16 | 257700906 |
17 | 980240880 |
18 | 3731753180 |
19 | 14222737200 |
20 | 54278580036 |
21 | 207438938000 |
22 | 793940475900 |
23 | 3043140078000 |
24 | 11681057249536 |
25 | 44900438149296 |
26 | 172824331826580 |
27 | 666070256489680 |
[0,0,0,6,48,260,1200,5106,20720,81876,318000, 1223136,4675440,17815020,67769552,257700906, 980240880,3731753180,14222737200,54278580036, 207438938000,793940475900,3043140078000, 11681057249536,44900438149296,172824331826580, 666070256489680] |