Dedicated to Professor Jozef T. Devreese on the occasion of his 65th birthday PACS 71.15.Mb For a one-body potential VðrÞ generating eigenfunctions w i ðrÞ and corresponding eigenvalues E i , the Feynman propagator Kðr; r 0 ; tÞ is simply related to the canonical density matrix Cðr; r 0 ; bÞ by b ! it: The diagonal element Sðr; r; bÞ of C is the so-called Slater sum of statistical mechanics. Differential equations for the Slater sum are first briefly reviewed, a quite general equation being available for a one-dimensional potential VðxÞ: This equation can be solved for a sech 2 potential, and some physical properties of interest such as the local density of states are derived by way of illustration. Then, the Coulomb potential ÀZe 2 =r is next considered, and it is shown that what is essentially the inverse Laplace transform of Sðr; bÞ=b can be calculated for an arbitrary number of closed shells. Blinder has earlier determined the Feynman propagator in terms of Whittaker functions and contact is here established with his work. The currently topical case of Fermion vapours which are harmonically confined is then treated, for both two and three dimensions. Finally, in an Appendix, a perturbation series for the Slater sum is briefly summarized, to all orders in the one-body potential VðrÞ: The corresponding kinetic energy is thereby accessible.