A Hydrogen-like atom has atomic number Z. Photons emitted in the electronic transitions from level n = 4 to level n = 3 in these atoms are used to perform photoelectric effect experiment on a target metal. The maximum kinetic energy of the photoelectrons generated is 1.95eV. If the photoelectric threshold wavelength for the target metal is 310nm, the value of Z is _______.  

[Given: $\mathrm{hc}=1240\mathrm{eV}-\mathrm{nm}$ and $\mathrm{Rhc}=13.6\mathrm{eV}$ where R is the Rydberg constant, h is the Planck’s constant and c is the speed of light in vacuum]