The one-dimensional pair contact process with a particle source is studied by using dynamical cluster mean-field approximations with sites up to n = 12. The results obtained for different levels of approximation become convergent especially for n ≥ 6 and allow us to derive reliable extrapolations to the limit n → ∞. At the zero source limit, the critical point exhibits a discontinuity whose magnitude vanishes with 1/n. The coherent anomaly analysis of data supports that the vanishing of order parameter and density of isolated particles has the same critical behavior. In contrast to an earlier prediction, the present approximation does not support the existence of critical behavior in the inactive phase where the frozen density of isolated particles depends on the initial state.PACS numbers: 02.70. Lq, 05.50.+q, 05.70.Ln, 64.60.Cn The study of phase transitions from active fluctuating phases into absorbing states has attracted considerable interest in the last decade [1,2]. The static exponents of these phase transitions belong frequently to the directed percolation (DP) universality class, however, there are also examples for new universality classes [3]. Open questions are related to the necessary conditions that can destroy this robust universal behavior. One of the simplest model showing static DP behavior is the pair contact process (PCP) which was proposed to realize a system involving infinitely many absorbing states [4]. Recently, Dickman et. al. introduced a modified PCP model to explore the robustness of DP transition [5]. In this model, each site of the one-dimensional lattice is either vacant or occupied by a single particle. A (randomly chosen) pair of nearest-neighbor particles is annihilated with a probability p or an additional particle is created around the given pair with a probability 1 − p if it is not forbidden by double occupancy. In the extended model, an external particle source is introduced that attempts to insert isolated particles with a rate of h. This system exhibits an active phase when p is smaller than a critical value, p c . For p ≥ p c the system evolves into a frozen (absorbing) state where the nearest-neighbor pairs are absent. Further details of the model can be found in Ref. [5]. This extended model was studied by Monte Carlo (MC) simulations and dynamical cluster mean-field approximation for quite large cluster sizes (ranged from n = 2 to 6). Some disturbing behaviors, however, remained unsolved. For example, the analytical predictions tend not monotonously toward the MC results for h > 0 when the cluster size is increased. Furthermore the analytical results shows a discontinuity in the variation of critical point p c if h → 0. This observation is surprising because the present approximation has proved to be satisfactory in many cases for n ≤ 6 [6]. It is expected that the further increase of cluster size will resolve these discrepancies.In this Brief Report, we discuss the results of dynamical mean-field approximations for cluster sizes as large as n = 12. The present a...