  This paper considers a nonlinear model for population dynamics with age
structure. The fertility rate with respect to age is non constant and has the
form proposed by [17]. Moreover, its multiplicative structure and the
multiplicative structure of mortality makes the model separable. In this
setting it is shown that the number of births in unit time is given by a system
of nonlinear ordinary differential equations. The steady state solution
together with the equilibrium solution is found explicitly.
