nmax = 200;
nout = 100;

A = [0:0.001:4];
X = 0.2 * ones(nmax,length(A));

for m = 1:length(A) do
 for n = 1: nmax - 1 do
  X(n+1,m) = A(m) * X(n,m) * (1.0 - X(n,m));
 end
end

plot(A,X(nout:nmax,:),'.r','markersize',1)