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A204550 as a simple table

na(n)
10
21
31
42
54
620
772
8288
9864
106624
1135424
12212544
131088640
1410056960
1575064320
16600514560
174147200000
1846664294400
19440681472000
204406814720000
2139103948800000
22515545067520000

[0,1,1,2,4,20,72,288,864,6624,35424,212544,
 1088640,10056960,75064320,600514560,4147200000,
 46664294400,440681472000,4406814720000,
 39103948800000,515545067520000]