By employing the coefficient extraction method from hypergeometric series, we shall establish numerous closed form evaluations for infinite series containing central binomial coefficients and harmonic numbers, including several conjectured ones made by Z.-W. Sun.
Citation: Chunli Li, Wenchang Chu. Infinite series about harmonic numbersinspired by Ramanujan–like formulae[J]. Electronic Research Archive, 2023, 31(8): 4611-4636. doi: 10.3934/era.2023236
By employing the coefficient extraction method from hypergeometric series, we shall establish numerous closed form evaluations for infinite series containing central binomial coefficients and harmonic numbers, including several conjectured ones made by Z.-W. Sun.
[1] | N. D. Baruah, B. C. Berndt, H. H. Chan, Ramanujan's series for $1/\pi$: a survey, Amer. Math. Monthly., 116 (2009), 567–587. https://doi.org/10.1080/00029890.2009.11920975 doi: 10.1080/00029890.2009.11920975 |
[2] | J. M. Borwein, P. B. Borwein, Pi and the AGM: A Study in Analytic Number Theory and Computational Complexity Wiley, New York, 1987. |
[3] | H. H. Chan, W. C. Liaw, Cubic modular equations and new Ramanujan–type series for $1/\pi$, Pacific J. Math., 192 (2000), 219–238. https://doi.org/10.2140/pjm.2000.192.219 doi: 10.2140/pjm.2000.192.219 |
[4] | W. Chu, Hypergeometric approach to Apéry–like series, Integral Transforms Spec. Funct., 28 (2017), 505–518. https://doi.org/10.1080/10652469.2017.1315416 doi: 10.1080/10652469.2017.1315416 |
[5] | W. Chu, Infinite series identities from the very–well–poised $\Omega$-sum, Ramanujan J., 55 (2021), 239–270. https://doi.org/10.1007/s11139-020-00259-w doi: 10.1007/s11139-020-00259-w |
[6] | W. Chu, Ramanujan–Like formulae for $\pi^{\pm1}$ via Gould–Hsu Inverse Series Relations, Ramanujan J., 56 (2021), 1007–1027. https://doi.org/10.1007/s11139-020-00337-z doi: 10.1007/s11139-020-00337-z |
[7] | W. Chu, Further Apéry–like series for Riemann zeta function, Math. Notes, 109 (2021), 136–146. https://doi.org/10.1134/S0001434621010168 doi: 10.1134/S0001434621010168 |
[8] | W. Chu, J. M. Campbell, Harmonic sums from the Kummer theorem, J. Math. Anal. Appl., 501 (2021), Article 125179; pp. 37. https://doi.org/10.1016/j.jmaa.2021.125179 doi: 10.1016/j.jmaa.2021.125179 |
[9] | S. Ramanujan, Modular equations and approximations to $\pi$, Q. J. Math. (Oxford), 45 (1914), 350–372. |
[10] | W. Chu, $q$-series reciprocities and further $\pi$-formulae, Kodai Math. J., 41 (2018), 512–530. https://doi.org/10.2996/kmj/1540951251 doi: 10.2996/kmj/1540951251 |
[11] | J. Guillera, Hypergeometric identities for 10 extended Ramanujan–type series, Ramanujan J., 15 (2008), 219–234. https://doi.org/10.1007/s11139-007-9074-0 doi: 10.1007/s11139-007-9074-0 |
[12] | W. Chu, Dougall's bilateral $_2H_2$-series and Ramanujan–like $\pi$-formulae, Math. Comp., 80 (2011), 2223–2251. https://doi.org/10.1090/S0025-5718-2011-02474-9 doi: 10.1090/S0025-5718-2011-02474-9 |
[13] | W. Chu, W. L. Zhang, Accelerating Dougall's $_5F_4$-sum and infinite series involving $\pi$, Math. Comp., 83 (2014), 475–512. https://doi.org/10.1090/S0025-5718-2013-02701-9 doi: 10.1090/S0025-5718-2013-02701-9 |
[14] | W. Chu, Hypergeometric series and the Riemann Zeta function, Acta Arith., 82 (1997), 103–118. https://doi.org/10.4064/aa-82-2-103-118 doi: 10.4064/aa-82-2-103-118 |
[15] | X. Y. Wang, W. Chu, Further Ramanujan–like series containing harmonic numbers and squared binomial coefficients, Ramanujan J., 52 (2020), 641–668. https://doi.org/10.1007/s11139-019-00140-5 doi: 10.1007/s11139-019-00140-5 |
[16] | X. Y. Wang, W. Chu, Series with harmonic–like numbers and squared binomial coefficients, Rocky Mountain J. Math., 52 (2022), 1849–1866. |
[17] | Z.-W. Sun, New Conjectures in Number Theory and Combinatorics (in Chinese), Harbin Institute of Technology, 2021. |
[18] | Z. -W. Sun, List of conjectural series for powers of π and other constants in "Ramanujan's Identities'. Press of Harbin Institute of Technology, 2021, Chapter 5: 205–261. |
[19] | Z.-W. Sun, Series with summands involving harmonic numbers, arXiv preprint, (2023), arXiv: 2210.07238. https://doi.org/10.48550/arXiv.2210.07238 |
[20] | E. D. Rainville, Special Functions, The Macmillan Company, New York, 1960. |
[21] | X. Chen, W. Chu, Dixon's $_3F_2(1)$-series and identities involving harmonic numbers and Riemann zeta function, Discrete Math., 310 (2010), 83–91. https://doi.org/10.1016/j.disc.2009.07.029 doi: 10.1016/j.disc.2009.07.029 |
[22] | L. Comtet, Advanced Combinatorics, Dordrecht–Holland, The Netherlands, 1974. https://doi.org/10.1007/978-94-010-2196-8 |
[23] | W. N. Bailey, Generalized Hypergeometric Series, Cambridge University Press, Cambridge, 1935. |
[24] | Y. A. Brychkov, Handbook of Special Functions, CRC Press Taylor & Francis Group, Boca Raton - London - New York, 2008. |
[25] | Per W. Karlsson, Clausen's hypergeometric function with variable $-1/8$ or $8$, Math. Sci. Res. Hot-Line, 4 (2000), 25–33. |
[26] | K. N. Boyadzhiev, Series with central binomial coefficients Catalan numbers, and harmonic numbers, J. Integer. Seq., 15 (2012), 3. |
[27] | W. Chu, D. Zheng, Infinite series with harmonic numbers and central binomial coefficients, Int. J. Number Theory, 5 (2009), 429–448. https://doi.org/10.1142/S1793042109002171 doi: 10.1142/S1793042109002171 |
[28] | C. Elsner, On sums with binomial coefficients, Fibonacci Quart., 43 (2005), 31–45. |
[29] | M. Genčev, Binomial sums involving harmonic numbers, Math. Slovaca, 61 (2011), 215–226. https://doi.org/10.2478/s12175-011-0006-5 doi: 10.2478/s12175-011-0006-5 |
[30] | D. H. Lehmer, Interesting series involving the central binomial coefficient, Amer. Math. Monthly, 92 (1985), 449–457. https://doi.org/10.1080/00029890.1985.11971651 doi: 10.1080/00029890.1985.11971651 |
[31] | A. S. Nimbran, P. Levrie, A. Sofo, Harmonic-binomial Euler-like sums via expansions of $(\arcsin x)^p$, RACSAM Rev. R. Acad. A., 116 (2022), pp. 23. https://doi.org/10.1007/s13398-021-01156-7 doi: 10.1007/s13398-021-01156-7 |
[32] | X. Y. Wang, W. Chu, Binomial series identities involving generalized harmonic numbers, Integers, 20 (2020), #A98. |
[33] | I. J. Zucker, On the series $ \sum_{k = 1}^{\infty} \binom2k{k}^{-1}k^{-n}$, J. Number Theory, 20 (1985), 92–102. https://doi.org/10.1016/0022-314X(85)90019-8 doi: 10.1016/0022-314X(85)90019-8 |
[34] | I. Gessel, D. Stanton, Strange evaluations of hypergeometric series, SIAM J. Math. Anal., 13 (1982), 295–308. https://doi.org/10.1137/0513021 doi: 10.1137/0513021 |
[35] | H. W. Gould, L. C. Hsu, Some new inverse series relations, Duke Math. J., 40 (1973), 885–891. https://doi.org/10.1215/S0012-7094-73-04082-9 doi: 10.1215/S0012-7094-73-04082-9 |
[36] | W. Chu, Inversion techniques and combinatorial identities: A unified treatment for the $_7F_6$-series identities, Collect. Math., 45 (1994), 13–43. |
[37] | V. J. W. Guo, X. Lian, Some $q$-congruences on double basic hypergeometric sums, J. Difference Equ. Appl., 27 (2021), 453–461. https://doi.org/10.1080/10236198.2021.1906236 doi: 10.1080/10236198.2021.1906236 |
[38] | C. Wei, On two double series for $\pi$ and their $q$-analogues, Ramanujan J., 60 (2023), 615–625. https://doi.org/10.1007/s11139-022-00615-y doi: 10.1007/s11139-022-00615-y |
[39] | J. Ablinger, Discovering and proving infinite binomial sums identities, Exp. Math., 26 (2017), 62–71. https://doi.org/10.1080/10586458.2015.1116028 |
[40] | K.-C. Au, Colored multiple zeta values, WZ-pairs and infinite sums, arXiv preprint, (2022), arXiv: 2212.02986. https://doi.org/10.48550/arXiv.2212.02986 |
[41] | Z.-W. Sun, New series for some special values of $L$-functions, Nanjing Univ. J. Math. Biquarterly, 32 (2015), 189–218. |
[42] | Z.-W. Sun, New series for powers of $\pi$ and related congruences, Electron. Res. Arch., 28 (2020), 1273–1342. https://doi.org/10.3934/era.2020070 doi: 10.3934/era.2020070 |
[43] | C. Wei, On two conjectural series for $\pi$ and their $q$-analogues, arXiv preprint, (2022), arXiv: 2211.11484. https://doi.org/10.48550/arXiv.2211.11484 |
[44] | C. Xu, J. Q. Zhao, Sun's three conjectures of Apéry-like sums involving harmonic numbers, J. Comb. Number Theory, 12 (2020), 209–216. |