n | a(n) |
---|---|
0 | 1 |
1 | 1 |
2 | 4 |
3 | 9 |
4 | 56 |
5 | 190 |
6 | 1704 |
7 | 7644 |
8 | 93120 |
9 | 516240 |
10 | 8136000 |
11 | 53523360 |
12 | 1047548160 |
13 | 7961241600 |
14 | 187132377600 |
15 | 1611967392000 |
16 | 44311886438400 |
17 | 426483893606400 |
18 | 13428757601280000 |
19 | 142790947407360000 |
20 | 5066854992138240000 |
21 | 58981696577556480000 |
22 | 2328441680297779200000 |
[1,1,4,9,56,190,1704,7644,93120,516240,8136000, 53523360,1047548160,7961241600,187132377600, 1611967392000,44311886438400,426483893606400, 13428757601280000,142790947407360000, 5066854992138240000,58981696577556480000, 2328441680297779200000] |