# A052840 (b-file synthesized from sequence entry)
0 0
1 0
2 2
3 9
4 56
5 450
6 4464
7 52920
8 731520
9 11566800
10 206035200
11 4083488640
12 89137843200
13 2124970848000
14 54929029478400
15 1530259226496000
16 45705137084006400
17 1456873475016960000
18 49362677881380864000