Differential (left) and cumulative (right) initial planetesimal mass function derived from the simulations. In the left panel, the points show unsmoothed “local” estimates of the mass function, and the lines show best-fit solutions derived using a maximum likelihood estimator assuming a power-law form. The simulation with the smallest particles (﹩\tau =0.006﹩; red) forms a significantly smaller total mass of planetesimals throughout the duration of the run, but no significant differences in the slope of the derived mass function are observed. The agreement between the points on the low-mass end of the cumulative function and the ﹩{M}_{p}^{-0.6}﹩ power law (dashed line) demonstrates that at small masses, the mass function is well represented by the single power-law fit that we have calculated.