n | a(n) |
---|---|
0 | 0 |
1 | 4 |
2 | 20 |
3 | 120 |
4 | 696 |
5 | 4060 |
6 | 23660 |
7 | 137904 |
8 | 803760 |
9 | 4684660 |
10 | 27304196 |
11 | 159140520 |
12 | 927538920 |
13 | 5406093004 |
14 | 31509019100 |
15 | 183648021600 |
16 | 1070379110496 |
17 | 6238626641380 |
18 | 36361380737780 |
19 | 211929657785304 |
20 | 1235216565974040 |
21 | 7199369738058940 |
22 | 41961001862379596 |
23 | 244566641436218640 |
[0,4,20,120,696,4060,23660,137904,803760,4684660, 27304196,159140520,927538920,5406093004, 31509019100,183648021600,1070379110496, 6238626641380,36361380737780,211929657785304, 1235216565974040,7199369738058940, 41961001862379596,244566641436218640] |