The regular-geometric-figure solution to the N-body problem is presented in
a very simple way. The Newtonian formalism is used without resorting to a
more involved rotating coordinate system. Those configurations occur for ot
her kinds of interactions beyond the gravitational ones for some special va
lues of the parameters of the forces. For the harmonic oscillator, in parti
cular, it is shown that the N-body problem is reduced to N one-body problem
s.