What is the mathematical expression for the wave function of a 2s orbital in quantum mechanics?

The mathematical expression for the wave function of a 2s orbital in quantum mechanics is (2s) (1/(42)) (Z/a)(3/2) (2 - Zr/a) e(-Zr/(2a)), where represents the wave function, Z is the atomic number, a is the Bohr radius, and r is the distance from the nucleus.