Time of core collapse t_cc in units of the dynamical time t_dyn as a function of the mass spectrum exponent α for MPC (empty red squares) and N-body (small black circles) simulations. A parabolic fit to the N-body simulations (thick green line) is superimposed. The MPC result is generally within the range spanned by the direct N-body realisations, except for a few values of α at the high end, where core collapse happens earlier in direct N-body simulations.