# A013197 (b-file synthesized from sequence entry)
0 0
1 1
2 0
3 0
4 4
5 -20
6 120
7 -560
8 2784
9 -7920
10 -24960
11 1034880
12 -14625536
13 172569280
14 -1661936640
15 12339608320
16 -13269651456
17 -1902800305920
18 53452617646080
19 -1037015219466240
20 16547577836929024
21 -208832669083243520