# A227457 (b-file synthesized from sequence entry)
1 1
2 2
3 9
4 68
5 720
6 9804
7 163184
8 3210192
9 72870120
10 1874721360
11 53905894152
12 1713195438624
13 59633476003920
14 2256257009704320
15 92196226214092800
16 4046446853549201664
17 189845257963376620800
18 9481546020840245199360
19 502242773970728703225600
20 28124368575613839072714240