A symmetric variation of a distribution of Kreweras and Poupard
\textit{G. Kreweras} and \textit{Y. Poupard} [Eur. J. Comb. 7, 141-149 (1986; Zbl 0647.05007)] discovered a refinement of Narayana numbers that gives solution for three enumeration problems on bridges. Their distribution has an inherent lack of symmetry. The present paper shows a symmetric analogue, based on counting non-intersecting pairs of lattice paths between two lattice points with respect to the number of left turns in the left path and the number of right turns in the right path.
scientific article; zbMATH DE number 168247