!LAbIRp9cT. ID: 59f4d1 April 30, 2018, 1:01 p.m. No.5713   🗄️.is 🔗kun

look at the values for

 

nn + 2d(n-1) + f - 1

 

They are always square. The square root is either equal to (b-a)/2 or f