  In the framework of the quark combination, we derive the yield formulas and
study the yield ratios of the hidden-charm pentaquark states in
ultra-relativistic heavy ion collisions. We propose some interesting yield
ratios which clearly exhibit the production relationships between different
hidden-charm pentaquark states. We show how to employ a specific quark
combination model to evaluate the yields of exotic $P_c^+(4380)$, $P_c^+(4450)$
and their partners on the basis of reproducing the yields of normal identified
hadrons, and execute the calculations in central Pb+Pb collisions at
$\sqrt{s_{NN}}= 2.76$ TeV as an example.
