# A013451 (b-file synthesized from sequence entry)
0 1
1 0
2 0
3 4
4 0
5 0
6 160
7 544
8 0
9 17920
10 261120
11 707584
12 3942400
13 149360640
14 1538068480
15 5242548224
16 111522611200
17 2782416732160
18 25458261360640
19 166243180478464
20 5279051703910400
21 109528131284500480