The $(t,q)$-Analogs of Secant and Tangent Numbers

Dominique Foata, Guo-Niu Han

Abstract


The secant and tangent numbers are given $(t,q)$-analogs with an explicit combinatorial interpretation. This extends, both analytically and combinatorially, the classical evaluations of the Eulerian and Roselle polynomials at $t=-1$.


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