# A004385 (b-file synthesized from sequence entry)
4 1
5 40
6 1128
7 27720
8 635376
9 13991544
10 300500200
11 6348337336
12 132601016340
13 2747472247520
14 56594002961496
15 1160681786387760
16 23726045489546400
17 483774556165488000
18 9844971586905715128
19 200044340275516722160