n | a(n) |
---|---|
1 | 0 |
2 | 0 |
3 | 0 |
4 | 6 |
5 | 48 |
6 | 260 |
7 | 1200 |
8 | 5100 |
9 | 20720 |
10 | 81828 |
11 | 318000 |
12 | 1222870 |
13 | 4675440 |
14 | 17813820 |
15 | 67769504 |
16 | 257695800 |
17 | 980240880 |
18 | 3731732200 |
19 | 14222737200 |
20 | 54278498154 |
21 | 207438936800 |
22 | 793940157900 |
23 | 3043140078000 |
24 | 11681056021300 |
25 | 44900438149248 |
26 | 172824327151140 |
27 | 666070256468960 |
[0,0,0,6,48,260,1200,5100,20720,81828,318000, 1222870,4675440,17813820,67769504,257695800, 980240880,3731732200,14222737200,54278498154, 207438936800,793940157900,3043140078000, 11681056021300,44900438149248,172824327151140, 666070256468960] |