This system is modeled by the Agekyan-Anosova map, which has a strange attractor at x equalspoint five and y equals zero. Jacobi's integral gives a conserved quantity for this system. Thisproblem can be solved by a slowly-converging series in powers of t to the one-third; that result wasby Sundman. The H two plus ion is a quantum version of this problem, which is often solved usingfirst-order perturbation theory. One restricted version of this problem displays five equilibriumpoints named for (*)) Lagrange.