function [ Pb ] = erlang_r( A,k )
%UNTITLED2 Summary of this function goes here
%   Detailed explanation goes here
b = zeros(k+1,1);
b(1) = erlang(A,0);
for j = 2:k+1 % j is position to store
    c = j-1;
    b(j) = (A.*b(j-1))./(A.*b(j-1) + c);
end

Pb = b(k+1);
end