# A356667 (b-file synthesized from sequence entry)
0 1
1 1
2 4
3 12
4 72
5 240
6 2520
7 10080
8 127680
9 816480
10 11037600
11 79833600
12 1514177280
13 12454041600
14 261655954560
15 2699348652000
16 62869385779200
17 711374856192000
18 19407798693803520
19 243290200817664000
20 7300765959334848000
21 102980278869910041600