n | a(n) |
---|---|
0 | 1 |
1 | 1 |
2 | 1 |
3 | 4 |
4 | 18 |
5 | 108 |
6 | 778 |
7 | 6756 |
8 | 68220 |
9 | 787472 |
10 | 10224702 |
11 | 147512052 |
12 | 2340963570 |
13 | 40527565260 |
14 | 760095923082 |
15 | 15352212731820 |
16 | 332228417589720 |
17 | 7668868648772700 |
18 | 188085259069430744 |
19 | 4884294069438337428 |
20 | 133884389812214097774 |
21 | 3863086904690670182596 |
[1,1,1,4,18,108,778,6756,68220,787472,10224702, 147512052,2340963570,40527565260,760095923082, 15352212731820,332228417589720,7668868648772700, 188085259069430744,4884294069438337428, 133884389812214097774,3863086904690670182596] |