Qmd1poly[x_, rho_] :=
Module[{P = {(1-rho) Exp[x*rho]}, a = rho Exp[-rho], i = Floor[x],
        y = x - Floor[x], v = {}, d = {1}, k = 1},
	Do [
	  AppendTo[v, -a/j];
	  P = Prepend[v P, Plus @@ P];
	  AppendTo[d, k *= y],
	{j, i}];
        1 - P . d
]