n | a(n) |
---|---|
0 | 1 |
1 | 1 |
2 | 1 |
3 | 4 |
4 | 12 |
5 | 60 |
6 | 340 |
7 | 2280 |
8 | 17220 |
9 | 151872 |
10 | 1459584 |
11 | 15624000 |
12 | 182318400 |
13 | 2316837600 |
14 | 31596570720 |
15 | 465582237120 |
16 | 7283287851840 |
17 | 121620647715840 |
18 | 2149774858183680 |
19 | 40196871701360640 |
20 | 790002144844738560 |
21 | 16364478334463078400 |
22 | 354458730544573132800 |
[1,1,1,4,12,60,340,2280,17220,151872,1459584, 15624000,182318400,2316837600,31596570720, 465582237120,7283287851840,121620647715840, 2149774858183680,40196871701360640, 790002144844738560,16364478334463078400, 354458730544573132800] |