The cross sections for antihydrogen formation in the n=1, 2, 3, 4, 5,
6, and 7 levels from antiproton-positronium collisions are computed in
the unitarized Born approximation (UBA). Twenty-seven physical states
of antihydrogen (1s-->7h) and ten physical states (1s-->4f) of positr
onium are included in the UBA basis. The peak cross section for antihy
drogen formation from excited positronium targets is much larger than
that from a ground-state positronium target at low incident energies.
The high-n antihydrogen levels make a significant contribution to the
total antihydrogen formation cross section, especially for incident po
sitronium atoms in the Ps(n=3) and Ps(n=4) levels.