Hello Anon! The asymmetry is that (-f,1) contains factors on n-1, and (e,1) contains factors of n.
Check out the a values in the image I'm attaching. The upper highlighted bar has a values that are 5(5-1) = 20 = a(n-1) and 5(5) = 25 = a * n
The lower highlighted bar contains a values that are 29(5-1) = 116 = b(n-1) and 29(5)=145 = bn