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A009266 as a simple table

na(n)
01
10
20
3-2
40
516
640
7-272
8-1792
95696
1097536
11-58112
12-6692224
13-14752256
14566971392
153293370624
16-57170149376
17-629890867200
186512209063936
19128178697854976
20-759960372641792
21-28999010130804736
2264032469498658816

[1,0,0,-2,0,16,40,-272,-1792,5696,97536,-58112,
 -6692224,-14752256,566971392,3293370624,
 -57170149376,-629890867200,6512209063936,
 128178697854976,-759960372641792,
 -28999010130804736,64032469498658816]