Münster J. of Math. 3 (2010), 129--150

Dominique Foata, Guo-Niu Han


Abstract. Based on the evaluation at t=-1 of the generating polynomial for the hyperoctahedral group by the number of descents, an observation recently made by Hirzebruch, a new q-secant number is derived by working with the Chow-Gessel q-polynomial involving the flag major index. Using the doubloon combinatorial model we show that this new q-secant number is a polynomial with positive integral coefficients, a property apparently hard to prove by analytical methods.

foata at unistra dot fr, guoniu dot han at unistra dot fr

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