  The nth row of Pascal's trinomial triangle gives coefficients of (1+x+x^2)^n.
Let g(n) denote the number of such coefficients that are odd. We review Moshe's
algorithm for evaluating asymptotics of g(n) -- this involves computing the
Lyapunov exponent for certain 2x2 random matrix products -- and then analyze
further examples with more terms and higher powers of x.
