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A221401 as a simple table

na(n)
10
21
36
456
5324
62196
713328
883680
9512752
103161248
1119384848
12118981520
13729388016
144471790032
1527407876144
16167983235088
171029494729904
186309251897744
1938665450224432
20236955187985936
211452135101851056

[0,1,6,56,324,2196,13328,83680,512752,3161248,
 19384848,118981520,729388016,4471790032,
 27407876144,167983235088,1029494729904,
 6309251897744,38665450224432,236955187985936,
 1452135101851056]