n | a(n) |
---|---|
0 | 1 |
1 | 4 |
2 | 18 |
3 | 92 |
4 | 532 |
5 | 3440 |
6 | 24552 |
7 | 191280 |
8 | 1612304 |
9 | 14597952 |
10 | 141123872 |
11 | 1449324992 |
12 | 15743376704 |
13 | 180203389696 |
14 | 2166381979264 |
15 | 27274611880704 |
16 | 358690234163456 |
17 | 4916123783848960 |
18 | 70076765972288000 |
19 | 1036967662211324928 |
20 | 15902394743591408640 |
[1,4,18,92,532,3440,24552,191280,1612304,14597952, 141123872,1449324992,15743376704,180203389696, 2166381979264,27274611880704,358690234163456, 4916123783848960,70076765972288000, 1036967662211324928,15902394743591408640] |