n | a(n) |
---|---|
0 | 1 |
1 | 4 |
2 | 21 |
3 | 126 |
4 | 819 |
5 | 5616 |
6 | 40014 |
7 | 293436 |
8 | 2200770 |
9 | 16805880 |
10 | 130245570 |
11 | 1021926780 |
12 | 8102419470 |
13 | 64819355760 |
14 | 522606055815 |
15 | 4242331511910 |
16 | 34645707347265 |
17 | 284459491903860 |
18 | 2346790808206845 |
19 | 19444838125142430 |
20 | 161745698950048395 |
21 | 1350224965148230080 |
[1,4,21,126,819,5616,40014,293436,2200770, 16805880,130245570,1021926780,8102419470, 64819355760,522606055815,4242331511910, 34645707347265,284459491903860,2346790808206845, 19444838125142430,161745698950048395, 1350224965148230080] |