n | a(n) |
---|---|
0 | 1 |
1 | 4 |
2 | 20 |
3 | 128 |
4 | 1040 |
5 | 10432 |
6 | 125248 |
7 | 1753600 |
8 | 28057856 |
9 | 505041920 |
10 | 10100839424 |
11 | 222218469376 |
12 | 5333243269120 |
13 | 138664325005312 |
14 | 3882601100165120 |
15 | 116478033004986368 |
16 | 3727297056159629312 |
17 | 126728099909427527680 |
18 | 4562211596739391258624 |
19 | 173364040676096868352000 |
20 | 6934561627043874735128576 |
[1,4,20,128,1040,10432,125248,1753600,28057856, 505041920,10100839424,222218469376,5333243269120, 138664325005312,3882601100165120, 116478033004986368,3727297056159629312, 126728099909427527680,4562211596739391258624, 173364040676096868352000, 6934561627043874735128576] |