Determining the chemical potential of confined quantum systems of bosonic and fermionic type

The relationship, expressing the particle number parameter of a confined quantum system (for instance an ideal bosonic or fermionic gas) in terms of the chemical potential, may be considered as an integral equation for determining the fugacity. Fugacity is obtained as infinte series in the increasing powers of the particle number, which is strongly convergent for the entire range of the thermodynamic parameters, including the region of the so called Bose-Einstein condensation. The asymptotic behavior of the expansion coefficients for increasing ordering number is studied and a simple rule for it is discovered.