Direct and inverse source problems for two-term time-fractional diffusion equation with Hilfer derivative

In this paper, we investigate direct and inverse source problems for the diffusion equation with two-term generalized fractional derivative (Hilfer derivative) in a rectangular domain. Using spectral expansion method, we derive two-term fractional differential equation together with appropriate initial condition (Cauchy problem). Based on solution of that Cauchy prob-lem, we represent solution of formulated problems as a combination of sinus and multinomial Mittag-Leffler function of two variables. Imposing certain conditions to the given data, we prove uniform convergence of certain infinite series.