# A355998 (b-file synthesized from sequence entry)
4 1
5 48
6 1728
7 62720
8 2457600
9 105815808
10 5017600000
11 261227298816
12 14860167413760
13 918839084134400
14 61439672177393700
15 4421589120000000000
16 340976534987475000000
17 28064307240230900000000
18 2456376885785930000000000