  We study trapped systems of bosons at zero temperature in three and two
dimensions. Conditions are fulfilled for the application of Gross-Pitaevskii
theory with a positive scattering length. Series expansions for ground-state
properties are obtained in both the noninteracting and the strong-coupling
(Thomas-Fermi) limits. From these expansions, analytic estimates are presented
in the form of two-point Pad\'e approximants. We explicitly show the
approximants for the total energy per particle and the chemical potential.
