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arXiv · 2506.01649

A Grammatical Calculus for the Ramanujan Polynomials

William Y. C. Chen·Amy M. Fu·Elena L. Wang
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Abstract

The Ramanujan polynomials arise in three intertwined contexts. As remarked by BerndtEvans-Wilson, no combinatorial perspective seems to be alluded to in the original definition of Ramanujan. On a different stage, Dumont-Ramamonjisoa uncovered a combinatorial structure underneath an equation also considered by Ramanujan. Around the same time, Shor came up with the same construction as a refinement of the classical formula of Cayley for trees. We present a labeling scheme for rooted trees by employing an extra label marking improper edges. Harnessed by this grammar, we develop a grammatical calculus for the Ramanujan polynomials heavily relying on the constant properties. Moreover, we provide a grammatical formulation of a correspondence that leads to the recurrence relation due to Berndt-Evans-Wilson and Shor.

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William Y. C. Chen, Amy M. Fu, Elena L. Wang. 2025-06-02. A Grammatical Calculus for the Ramanujan Polynomials. https://arxiv.org/abs/2506.01649

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