Equation for the energy of an particle oscillator?

[AATroop]

So, my book claims that the effective spring stiffness of an atom (according to the Einstein model) is 2k_s,i, but in an example problem they state one quantum of energy for an oscillator with an interatomic spring stiffness of 5N/m with 5 quanta is
[itex]\hbar \times \sqrt(\frac{4(5)}{\mathrm{weight of atoms}})[/itex]

But, shouldn't it be

[itex]\hbar \times \sqrt(\frac{\Huge{2}(5)}{\mathrm{weight of atoms}})[/itex]

If it's too difficult to understand, could someone just provide the standard equation involving Planck's constant[itex]/2\pi[/itex] and the effective interatomic spring stiffness of an oscillator?

 

[jbsteele]

The equation for the energy of an oscillator with an interatomic spring stiffness of k is given by: E = nh\sqrt(k/m),where n is the number of quanta, h is Planck's constant, and m is the mass of the oscillator.