  A two-parametric fractional statistics is proposed, which can be used to
model a weakly-interacting Bose-system. It is shown that the parameters of the
introduced weakly nonadditive Polychronakos statistics can be linked to effects
of interactions as well as finite-size corrections. The calculations of the
specific heat and condensate fraction of the model system corresponding to
harmonically trapped Rb-87 atoms are made. The behavior of the specific heat of
three-dimensional isotropic harmonic oscillators with respect to the values of
the statistics parameters is studied in the temperature domain including the
BEC-like phase transition point.
