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A066988 as a simple table

na(n)
21
32
42
58
68
748
864
9192
10384
113840
125120
1361440
14184320
15737280
161474560
1723592960
1847185920
19849346560
202264924160
2113589544960
2267947724800
231494849945600
242989699891200
2529896998912000
26179381993472000

[1,2,2,8,8,48,64,192,384,3840,5120,61440,184320,
 737280,1474560,23592960,47185920,849346560,
 2264924160,13589544960,67947724800,1494849945600,
 2989699891200,29896998912000,179381993472000]