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A180878 as a simple table

na(n)
11
20
3-1
4-1
5-9
6-5
7-21
8-21
9-197
10-117
11-427
12-427
13-2501
14-1797
15-2909
16-2909
17-72877
18-65453

[1,0,-1,-1,-9,-5,-21,-21,-197,-117,-427,-427,
 -2501,-1797,-2909,-2909,-72877,-65453]