# A051197 (b-file synthesized from sequence entry)
0 0
1 6
2 24
3 120
4 480
5 2002
6 7952
7 31824
8 125760
9 497420
10 1960464
11 7726160
12 30418752
13 119759850
14 471424160
15 1855967520
16 7307828352
17 28781143380
18 113380093840
19 446775310800
20 1761038703424
21 6943526580276
22 27385654785504