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A000980 as a simple table

na(n)
02
14
28
320
452
5152
6472
71520
85044
917112
1059008
11206260
12729096
132601640
149358944
1533904324
16123580884
17452902072
181667837680
196168510256
2022903260088
2185338450344
22318995297200
231195901750512
244495448217544
2516940411201280
2663983233268592

[2,4,8,20,52,152,472,1520,5044,17112,59008,206260,
 729096,2601640,9358944,33904324,123580884,
 452902072,1667837680,6168510256,22903260088,
 85338450344,318995297200,1195901750512,
 4495448217544,16940411201280,63983233268592]