n | a(n) |
---|---|
1 | 1 |
2 | 4 |
3 | 20 |
4 | 60 |
5 | 180 |
6 | 540 |
7 | 4860 |
8 | 19440 |
9 | 58320 |
10 | 174960 |
11 | 2274480 |
12 | 6823440 |
13 | 20470320 |
14 | 184232880 |
15 | 552698640 |
16 | 1658095920 |
17 | 31503822480 |
18 | 94511467440 |
19 | 283534402320 |
20 | 850603206960 |
21 | 7655428862640 |
22 | 99520575214320 |
23 | 2488014380358000 |
[1,4,20,60,180,540,4860,19440,58320,174960, 2274480,6823440,20470320,184232880,552698640, 1658095920,31503822480,94511467440,283534402320, 850603206960,7655428862640,99520575214320, 2488014380358000] |