# A355171 (b-file synthesized from sequence entry)
0 0
1 1
2 7
3 50
4 406
5 3804
6 41028
7 506064
8 7084656
9 111690720
10 1967421600
11 38425449600
12 825970435200
13 19404363283200
14 495012834489600
15 13632039812966400
16 403120633444300800
17 12740557701389414400
18 428546132879432601600
19 15284163618598275072000
20 576073025410937628672000