n | a(n) |
---|---|
0 | 1 |
1 | 1 |
2 | 4 |
3 | 30 |
4 | 240 |
5 | 2433 |
6 | 26388 |
7 | 315726 |
8 | 3958452 |
9 | 51863952 |
10 | 698988716 |
11 | 9637772716 |
12 | 135161761860 |
13 | 1920878419569 |
14 | 27583547221596 |
15 | 399310273694328 |
16 | 5817100622299116 |
17 | 85152975761167179 |
18 | 1251046169511714720 |
19 | 18428780031111768466 |
20 | 271964652432415737596 |
[1,1,4,30,240,2433,26388,315726,3958452,51863952, 698988716,9637772716,135161761860,1920878419569, 27583547221596,399310273694328,5817100622299116, 85152975761167179,1251046169511714720, 18428780031111768466,271964652432415737596] |