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    November 09

    The Refined Lives of the F- and H-Vectors of Associahedra

    The compositional inversions noted in the Oct. 9-th entry "Flipping
    Functions with Permutohedra" have counterparts with respect to the
    associahedra, or Stasheff polytopes. The h-polynomials of the
    associahedra (see the Narayana number triangle OEIS-A001263) can be
    refined as OEIS-A134264 for the coefficients of an indirect Lagrange
    method for determining the compositional inverse of a function,
    whereas the corresponding f-polynomials (see OEIS-A033282) can be
    refined as the unsigned polynomials in OEIS-A133437 (or A111785) for
    the coefficients of a Lagrange inversion for an ordinary generating
    function. (OEIS denotes the Online Encyclopedia of Integer Sequences.)