Determine the radius of convergence of the power series sigma_n = 1^infinity (-2)^n (n-3)^n/n. if y is a solution of the initial problem xy" + (in x)y' + (x^2 + 1)y = 0, y(1) = 2, y'(1) = -1, then y"(1) = and y^(3)(1) = .