  With data taken by SELEX, which accumulated data during the 1996-1997 fixed
target run at Fermilab, we study the production of charmed hadrons on copper
and carbon targets with Sigma-, p, pi-, and pi+ beams. Parameterizing the
production cross section A^alpha, A being the atomic number, we determine alpha
for D+, D0, Ds+, D+(2010), Lambda_c+, and their respective anti-particles, as a
function of their transverse momentum pt and scaled longitudinal momentum xF.
Within our statistics there is no dependence of alpha on xF for any charm
species for the interval 0.1<xF<1.0. The average value of alpha for charm
production by pion beams is alpha_{meson}=0.850+/-0.028. This is somewhat
larger than the corresponding average alpha_{baryon}=0.755+/-0.016 for charm
production by baryon beams (Sigma-, p).
