Let $ \lambda_{f}(n) $ be the $ n $-th normalized Fourier coefficient of $ f $, which is a primitive holomorphic cusp form of even integral weight $ k\geq2 $ for the full modular group $ SL_2(\mathbb{Z}) $. Let also $ \sigma(n) $ and $ \phi(n) $ be the sum-of-divisors function and the Euler totient function, respectively. In this paper, we are able to establish the asymptotic formula of the sum of the hybrid arithmetic function $ \lambda_{f}^{l}(n)\sigma^{c}(n)\phi^{d}(n) $ over the sparse sequence $ \{n: n = a^2+b^2\} $, namely, $ \sum_{n\leq x} \lambda_{f}^{l}(n)\sigma^{c}(n)\phi^{d}(n)r_2(n) $ for $ 1\leq l\leq 8 $, where $ x $ is a sufficiently large real number, the function $ r_2(n) $ denotes the number of representations of $ n $ as $ n = a^2 + b^2 $, $ a, b, l\in \mathbb{Z} $ and $ c, d \in \mathbb{R} $.
Citation: Huafeng Liu, Rui Liu. The sum of a hybrid arithmetic function over a sparse sequence[J]. AIMS Mathematics, 2024, 9(2): 4830-4843. doi: 10.3934/math.2024234
Let $ \lambda_{f}(n) $ be the $ n $-th normalized Fourier coefficient of $ f $, which is a primitive holomorphic cusp form of even integral weight $ k\geq2 $ for the full modular group $ SL_2(\mathbb{Z}) $. Let also $ \sigma(n) $ and $ \phi(n) $ be the sum-of-divisors function and the Euler totient function, respectively. In this paper, we are able to establish the asymptotic formula of the sum of the hybrid arithmetic function $ \lambda_{f}^{l}(n)\sigma^{c}(n)\phi^{d}(n) $ over the sparse sequence $ \{n: n = a^2+b^2\} $, namely, $ \sum_{n\leq x} \lambda_{f}^{l}(n)\sigma^{c}(n)\phi^{d}(n)r_2(n) $ for $ 1\leq l\leq 8 $, where $ x $ is a sufficiently large real number, the function $ r_2(n) $ denotes the number of representations of $ n $ as $ n = a^2 + b^2 $, $ a, b, l\in \mathbb{Z} $ and $ c, d \in \mathbb{R} $.
[1] | P. Deligne, La conjecture de Weil. Ⅰ, Publ. Math. Inst. Hautes Études Sci., 43 (1974), 273–307. https://doi.org/10.1007/BF02684373 doi: 10.1007/BF02684373 |
[2] | E. Hecke, Theorie der eisensteinsche reihen höherer stufe und ihre anwendung auf funktionen-theorie und arithmetik, Abhandlungen Math. Semin. Univ. Hamb., 5 (1927), 199–224. https://doi.org/10.1007/BF02952521 doi: 10.1007/BF02952521 |
[3] | J. Wu, Power sums of Hecke eigenvalues and application, Acta Arith., 137 (2009), 333–344. https://doi.org/10.4064/aa137-4-3 doi: 10.4064/aa137-4-3 |
[4] | R. A. Rankin, Contributions to the theory of Ramanujan's function $\tau(n)$ and similar arithmetical functions, Math. Proc. Cambridge Philos. Soc., 35 (1939), 351–372. https://doi.org/10.1017/S0305004100021101 doi: 10.1017/S0305004100021101 |
[5] | A. Selberg, V. Bjerknes, J. Molland, Bemerkungen über eine Dirichletsche Reihe, die mit der theorie der modulformen nahe verbunden ist, Cammermeyer i Komm, 1940. |
[6] | B. R. Huang, On Rankin-Selberg problem, Math. Ann., 381 (2021), 1217–1251. https://doi.org/10.1007/s00208-021-02186-7 doi: 10.1007/s00208-021-02186-7 |
[7] | Y. K. Lau, G. S. Lü, Sums of Fourier coefficients of cusp forms, Q. J. Math., 62 (2011), 687–716. https://doi.org/10.1093/qmath/haq012 doi: 10.1093/qmath/haq012 |
[8] | C. R. Xu, General asymptotic formula of Fourier coefficients of cusp forms over sum of two squares, J. Number Theory, 236 (2022), 214–229. https://doi.org/10.1016/j.jnt.2021.07.017 doi: 10.1016/j.jnt.2021.07.017 |
[9] | S. Zhai, Average behavior of Fourier coefficients of cusp forms over sum of two squares, J. Number Theory, 133 (2013), 3862–3876. https://doi.org/10.1016/j.jnt.2013.05.013 doi: 10.1016/j.jnt.2013.05.013 |
[10] | H. F. Liu, On the asymptotic distribution of Fourier coefficients of cusp forms, Bull. Braz. Math. Soc., 54 (2023), 21. https://doi.org/10.1007/s00574-023-00335-x doi: 10.1007/s00574-023-00335-x |
[11] | S. Manski, J. Mayle, N. Zbacnik, The asymptotic distribution of a hybrid arithmetic function, Integers, 15 (2015), A28. https://doi.org/10.5281/zenodo.10456207 doi: 10.5281/zenodo.10456207 |
[12] | L. L. Wei, H. X. Lao, The mean value of a hybrid arithmetic function associated to Fourier coefficients of cusp forms, Integers, 19 (2019), A44. |
[13] | H. Iwaniec, Topics in classical automorphic forms, Providence, Rhode lsland: American Mathematical Society, 1997. https://doi.org/10.1090/gsm/017 |
[14] | J. Newton, J. A. Thorne, Symmetric power functoriality for holomorphic modular forms, Publ. Math. l'IHÉS, 134 (2021), 1–116. https://doi.org/10.1007/s10240-021-00127-3 doi: 10.1007/s10240-021-00127-3 |
[15] | J. Newton, J. A. Thorne, Symmetric power functoriality for holomorphic modular forms, Publ. Math. l'IHÉS, 134 (2021), 117–152. https://doi.org/10.1007/s10240-021-00126-4 doi: 10.1007/s10240-021-00126-4 |
[16] | A. Perelli, General $L$-functions, Ann. Mat. Pura Appl., 4 (1982), 287–306. https://doi.org/10.1007/BF01761499 doi: 10.1007/BF01761499 |
[17] | J. Bourgain, Decoupling, exponential sums and the Riemann zeta function, J. Amer. Math. Soc., 30 (2017), 205–224. https://doi.org/10.1090/jams/860 doi: 10.1090/jams/860 |
[18] | Y. Lin, R. Nunes, Z. Qi, Strong subconvexity for self-dual $GL(3)$ $L$-functions, Int. Math. Res. Not., 2023 (2023), 11453–11470. https://doi.org/10.1093/imrn/rnac153 doi: 10.1093/imrn/rnac153 |
[19] | K. Matsumoto, The mean values and the university of Rankin-Selberg $L$-functions, Number Theory, 2001,201–221. |
[20] | K. Ramachandra, A. Sankaranarayanan, Notes on the Riemann zeta-function, J. Indian Math. Soc., 57 (1991), 67–77. |
[21] | A. Ivić, Exponent pairs and the zeta function of Riemann, Studia Sci. Math. Hunger., 15 (1980), 157–181. |
[22] | G. Tenenbaum, Introduction to analytic and probabilistic number theory, Cambridge University Press, 1995. https://doi.org/10.1090/gsm/163 |