# A004384 (b-file synthesized from sequence entry)
3 1
4 32
5 780
6 17296
7 367290
8 7624512
9 156238908
10 3176716400
11 64276915527
12 1296543270880
13 26100986351440
14 524780754733872
15 10542859559688820
16 211709328983644800
17 4250305029168216000
18 85323087086516197776