x^(2n+1) + y^(2n+1) = x^(2n+1) - y^(2n-1)*x^2 + y^(2n-1)*x^2 + y^(2n+1)
= x^2(x^(2n-1) + y^(2n-1)) + y^(2n-1)(x^2 - y^2)