Polynomial

[EandH]

Hello, can someone help me find the polynomal for the sum of the darker areas in the square?[attachment=0:zybc0469]graph.PNG[/attachment:zybc0469]

 

[Aladdin]

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Sum of dark areas : 8*(n-4) + (n-8)*(n-4) + 4*(n-8)

 

[Denis]

Simply n^2 - 32 (whole square less white portion!)