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A189870 as a simple table

na(n)
11
20
30
42
52
64
728
80
920
1052
11280
121192
135520
1420196
15115936
16701836
174174032
1827261284
19193428616
201445733328
2111133210948

[1,0,0,2,2,4,28,0,20,52,280,1192,5520,20196,
 115936,701836,4174032,27261284,193428616,
 1445733328,11133210948]