n | a(n) |
---|---|
1 | 1 |
2 | 4 |
3 | 20 |
4 | 104 |
5 | 552 |
6 | 2972 |
7 | 16172 |
8 | 88720 |
9 | 489872 |
10 | 2719028 |
11 | 15157188 |
12 | 84799992 |
13 | 475894200 |
14 | 2677788492 |
15 | 15102309468 |
16 | 85347160608 |
17 | 483183316512 |
18 | 2739851422820 |
19 | 15558315261812 |
20 | 88462135512712 |
21 | 503569008273992 |
22 | 2869602773253884 |
23 | 16368396446913420 |
24 | 93449566652932784 |
25 | 533954950648248752 |
[1,4,20,104,552,2972,16172,88720,489872,2719028, 15157188,84799992,475894200,2677788492, 15102309468,85347160608,483183316512, 2739851422820,15558315261812,88462135512712, 503569008273992,2869602773253884, 16368396446913420,93449566652932784, 533954950648248752] |