  We measure on the lattice the quenched pseudoscalar and vector meson masses
at a fixed value of the lattice spacing for SU(N) gauge theory with fermions in
the adjoint, in the symmetric and in the antisymmetric representations of the
gauge group. Simulations are performed for N=3,4,6 in all those
representations, with the addition of N=2 for the adjoint representation. We
illustrate a strategy for separating the even from the odd-power contributions
in 1/N in the masses. Using this technique, we extrapolate the vector mass to
the large-N limit in the chiral region and show that at N = infty this mass is
the same within errors in all the three representations, as predicted by
orientifold planar equivalence. Possible implications of our investigation for
studying orientifold planar equivalence in the dynamical case are discussed.
