Resonance frequency of a cantilever beam is given by

f=(kn/2pi)*sqrt(EI/mL4)

where, kn=3.52 for cantilever, E is Young's Modulus, I is moment of Inertia, m is mass, L is beam length.

The equation is available in Raymond J. Roark and Warren C. Young, “Formulas for Stress and Strain”, McGraw-Hill, Kogakusha, 5th Edition, (1976).