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A009186 as a simple table

na(n)
01
1-1
22
3-6
416
5-72
6328
7-1848
811712
9-81088
10638720
11-5318016
1249459840
13-483162240
145159926528
15-57865303296
16697030680576
17-8815813734400
18118233272496128
19-1662921003208704
2024578235697610752
21-380141599264751616
226139851821419921408

[1,-1,2,-6,16,-72,328,-1848,11712,-81088,638720,
 -5318016,49459840,-483162240,5159926528,
 -57865303296,697030680576,-8815813734400,
 118233272496128,-1662921003208704,
 24578235697610752,-380141599264751616,
 6139851821419921408]