Discovering hypergeometric series with harmonic numbers via Wilf-Zeilberger seeds
Kam Cheong Au
TL;DR
This work extends the Wilf-Zeilberger framework by using WZ-seeds, a parametric generalization that yields families of WZ-pairs from which coefficients are extracted to produce hypergeometric series with harmonic-number factors. The authors obtain a rapidly convergent series for the depth-two MZV $ζ(5,3)$ and conjecture a simple Hilbert-Poincaré function for the coefficient spaces, suggesting an underlying graded-algebra structure with five generators. Across explicit constructions and numerous examples, they connect parameter-extracted series to MZVs, Ramanujan-type $1/π$ formulas, and broader algebraic structures, highlighting both rigorous identities and conjectural relations. The framework provides a systematic route to discover and organize new hypergeometric-harmonic identities with potential deepening insights into the algebraic organization of MZVs and related constants.
Abstract
By extracting coefficients from Wilf-Zeilberger pairs with respect to auxiliary parameters, we discover many nontrivial hypergeometric series involving harmonic numbers. In particular, we obtain a rapidly convergent series for the depth-two multiple zeta value $ζ(5,3)$, which appears to be the first result of its kind in the literature. We also experiment with the Hilbert-Poincare series attached with a WZ-seed and conjecture that it admits a remarkably simple form, suggesting the presence of an underlying graded algebra structure behind WZ-seeds.
