n | a(n) |
---|---|
0 | 1 |
1 | 4 |
2 | 20 |
3 | 112 |
4 | 656 |
5 | 3904 |
6 | 23360 |
7 | 140032 |
8 | 839936 |
9 | 5039104 |
10 | 30233600 |
11 | 181399552 |
12 | 1088393216 |
13 | 6530351104 |
14 | 39182090240 |
15 | 235092508672 |
16 | 1410554986496 |
17 | 8463329787904 |
18 | 50779978465280 |
19 | 304679870267392 |
20 | 1828079220555776 |
[1,4,20,112,656,3904,23360,140032,839936,5039104, 30233600,181399552,1088393216,6530351104, 39182090240,235092508672,1410554986496, 8463329787904,50779978465280,304679870267392, 1828079220555776] |