# A174782 (b-file synthesized from sequence entry)
1 0
2 1
3 3
4 54
5 250
6 1950
7 10206
8 64288
9 350064
10 2065500
11 11509300
12 66905256
13 380767608
14 2226036904
15 12949377000
16 76842172800
17 457297336576
18 2766381692688
19 16849247813424
20 104116268476000
21 649043824951200