We study Ramanujan-Fourier series of certain arithmetic functions of two variables. We generalize Delange's theorem to the case of arithmetic functions of two variables and give sufficient conditions for pointwise convergence of Ramanujan-Fourier series of arithmetic functions of two variables. We also give several examples which are not obtained by trivial generalizations of results on Ramanujan-Fourier series of functions of one variable.
Ramanujan expansions of arithmetic functions of several variables
On error term estimates à la Walfisz for mean values of arithmetic functions
Higher uniformity of arithmetic functions in short intervals II. Almost all intervals
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