An infinitely long wire carrying a current I is bent in the shape of the parabola y = ax² (with the current flowing from left to right). Find the magnetic field generated by this wire at the point (0, y) (the field will point out of the page, in the z direction). You may leave your answer in integral form.

Reference: Electrodynamics, 4th Edition by David Griffiths

Note: This problem is not from the textbook. All information needed to solve the problem is included in the question; there are no relevant figures or additional information.