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A291390 as a simple table

na(n)
02
117
2130
3940
46550
544475
6296250
71944375
812612500
981035000
10516537500
113270615625
1220591031250
13128998328125
14804673593750
155000444062500
1630969644531250
17191231146484375
181177627753906250
197234317013671875
2044342955390625000
21271252632343750000

[2,17,130,940,6550,44475,296250,1944375,12612500,
 81035000,516537500,3270615625,20591031250,
 128998328125,804673593750,5000444062500,
 30969644531250,191231146484375,1177627753906250,
 7234317013671875,44342955390625000,
 271252632343750000]