n | a(n) |
---|---|
0 | 1 |
1 | 1 |
2 | 4 |
3 | 22 |
4 | 140 |
5 | 969 |
6 | 7084 |
7 | 53820 |
8 | 420732 |
9 | 3362260 |
10 | 27343888 |
11 | 225568798 |
12 | 1882933364 |
13 | 15875338990 |
14 | 134993766600 |
15 | 1156393243320 |
16 | 9969937491420 |
17 | 86445222719724 |
18 | 753310723010608 |
19 | 6594154339031800 |
20 | 57956002331347120 |
21 | 511238042454541545 |
[1,1,4,22,140,969,7084,53820,420732,3362260, 27343888,225568798,1882933364,15875338990, 134993766600,1156393243320,9969937491420, 86445222719724,753310723010608,6594154339031800, 57956002331347120,511238042454541545] |