k = 3  I = [y^3 + x^2, y^4]  integral closure gens: [y^3 + x^2, y^4, x*y^3]
   y^k in closure: False   x^2 in closure: False   x*y^(k-2)... (x y^((k-1)/2)) in closure: False
k = 5  I = [y^5 + x^2, y^8]  integral closure gens: [y^5 + x^2, y^8, x*y^6]
   y^k in closure: False   x^2 in closure: False   x*y^(k-2)... (x y^((k-1)/2)) in closure: False
k = 7  I = [y^7 + x^2, y^12]  integral closure gens: [y^7 + x^2, y^12, x*y^9]
   y^k in closure: False   x^2 in closure: False   x*y^(k-2)... (x y^((k-1)/2)) in closure: False