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A155221 as a simple table

na(n)
21
37
425
570
6500
77410
881126
91254921
1035099024
111318005942
1258686994598
133824088664649
14368413623404582
1547231934784100638
168189977602765893624

[1,7,25,70,500,7410,81126,1254921,35099024,
 1318005942,58686994598,3824088664649,
 368413623404582,47231934784100638,
 8189977602765893624]