Abstract
The effect of blocking, for odd systems, is included in the gap equations of the nuclear pairing theory for a general two-body interaction. These equations are applied to calculate the one-quasiparticle low-energy spectra, the neutron separation energies, and the "odd-even mass differences" for the Sn isotopes. The apparent inflation of the effective pairing strengths in calculations in which the blocking effect is ignored is pointed out.