English

On series identities involving $\binom{4k}k$ and harmonic numbers

Number Theory 2026-01-27 v1 Combinatorics

Abstract

The harmonic numbers are those Hn=0<kn1k (n=0,1,2,)H_n=\sum_{0<k\le n}\frac1k\ (n=0,1,2,\ldots). In this paper we confirm over ten conjectural series identities with summands involving the binomial coefficient (4kk)\binom{4k}k and harmonic numbers. For example, we prove the identities k=1(4kk)16k((22k292k+11)H4k449k27528512k)=151803log2\sum_{k=1}^\infty \frac{\binom{4k}{k}}{16^k}\left((22k^2-92k+11)H_{4k}-\frac{449k-275}{2}-\frac{85}{12k}\right)=-151-\frac{80}{3}\log{2} and k=0(4kk)((11k2+8k+1)(10H4k17H2k)+2k+18)(3k+1)(3k+2)16k=8log2, \sum_{k=0}^\infty\frac{\binom{4k}{k}((11k^2+8k+1)(10H_{4k}-17H_{2k})+2k+18)}{(3k+1)(3k+2)16^k}=8\log2, which were previously conjectured by Z.-W. Sun.

Keywords

Cite

@article{arxiv.2601.18645,
  title  = {On series identities involving $\binom{4k}k$ and harmonic numbers},
  author = {Bo Jiang and Zhi-Wei Sun},
  journal= {arXiv preprint arXiv:2601.18645},
  year   = {2026}
}

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22 pages