n | a(n) |
---|---|
0 | 1 |
1 | 2 |
2 | 18 |
3 | 140 |
4 | 1330 |
5 | 12852 |
6 | 130284 |
7 | 1348776 |
8 | 14247090 |
9 | 152618180 |
10 | 1654120468 |
11 | 18096447096 |
12 | 199536967084 |
13 | 2214714164600 |
14 | 24720932068200 |
15 | 277289164574640 |
16 | 3123590583844530 |
17 | 35318969120870820 |
18 | 400692715550057700 |
19 | 4559427798654821400 |
20 | 52020436064931914580 |
[1,2,18,140,1330,12852,130284,1348776,14247090, 152618180,1654120468,18096447096,199536967084, 2214714164600,24720932068200,277289164574640, 3123590583844530,35318969120870820, 400692715550057700,4559427798654821400, 52020436064931914580] |