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arXiv · 2305.00626

On two-term hypergeometric recursions with free lower parameters

John M. Campbell·Paul Levrie
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Abstract

Let $F(n,k)$ be a hypergeometric function that may be expressed so that $n$ appears within initial arguments of inverted Pochhammer symbols, as in factors of the form $\frac{1}{(n)_{k}}$. Only in exceptional cases is $F(n, k)$ such that Zeilberger's algorithm produces a two-term recursion for $\sum_{k = 0}^{\infty} F(n, k)$ obtained via the telescoping of the right-hand side of a difference equation of the form $p_{1}(n) F(n + r, k) + p_{2}(n) F(n, k) = G(n, k+1) - G(n, k)$ for fixed $r \in \mathbb{N}$ and polynomials $p_{1}$ and $p_{2}$. Building on the work of Wilf, we apply a series acceleration technique based on two-term hypergeometric recursions derived via Zeilberger's algorithm. Fast converging series previously given by Ramanujan, Guillera, Chu and Zhang, Chu, Lupa\c{s}, and Amdeberhan are special cases of hypergeometric transforms introduced in our article.

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John M. Campbell, Paul Levrie. 2023-05-01. On two-term hypergeometric recursions with free lower parameters. https://arxiv.org/abs/2305.00626

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