Observed richness λ (left panel) and intrinsic richness λ_* (central panel) as a function of redshift obtained with AMICO. For redshifts higher than z = 0.56, the cutoff magnitude m_cut = m_* + 1.5, on which λ_* is based, falls below the detection limit and the richness is underestimated, as is clear from the lack of rise in the λ_* of detections with z > 0.56. The right panel shows the amplitude, A, of the detections. The blue and red symbols refer to detections with S/N > 3 and S/N < 3, respectively.