{ "id": "2401.14197", "version": "v1", "published": "2024-01-25T14:18:15.000Z", "updated": "2024-01-25T14:18:15.000Z", "title": "Proof of conjectures on series with summands involving $ \\binom{2k}{k}8^k/(\\binom{3k}{k}\\binom{6k}{3k})$", "authors": [ "Zhi-Wei Sun", "Yajun Zhou" ], "comment": "23 pages, 5 tables. A sequel to arXiv:2401.12083v1", "categories": [ "math.CA", "math.NT" ], "abstract": "Using cyclotomic multiple zeta values of level $8$, we confirm and generalize several conjectural identities on infinite series with summands involving $\\binom{2k}k8^k/(\\binom{3k}k\\binom{6k}{3k})$. For example, we prove that \\[\\sum_{k=0}^\\infty\\frac{(350k-17)\\binom{2k}k8^k} {\\binom{3k}k\\binom{6k}{3k}}=15\\sqrt2\\,\\pi+27\\] and \\[\\sum_{k=1}^\\infty\\frac{\\left\\{(5k-1)\\left[16\\mathsf H_{2k-1}^{(2)}-3\\mathsf H_{k-1}^{(2)}\\right]-\\frac{12(6k-1)}{(2k-1)^2}\\right\\}\\binom{2k}k8^k} {k(2k-1)\\binom{3k}k\\binom{6k}{3k}}=\\frac{\\pi^3}{12\\sqrt2},\\] where $\\mathsf H^{(2)}_m$ denotes the second-order harmonic number $\\sum_{0