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A009391 as a simple table

na(n)
00
11
2-1
33
4-4
525
6-61
7427
8-1184
912465
10-49201
11555731
12-2361844
1335135945
14-191422141
152990414715
16-17147588384
17329655706465
18-2289437638081
1945692713833379
20-329955144475204
217777794952988025
22-65643617893832221

[0,1,-1,3,-4,25,-61,427,-1184,12465,-49201,555731,
 -2361844,35135945,-191422141,2990414715,
 -17147588384,329655706465,-2289437638081,
 45692713833379,-329955144475204,7777794952988025,
 -65643617893832221]