This paper aims to establish conditions for the existence, uniqueness and Ulam–Hyers
stability of solutions for a coupled system of pantograph problem with three sequential
fractional derivatives. Two results on the uniqueness and existence of solutions are proved
to utilize the Leray–Schauder and Banach fixed point theorems and positive contraction-type
inequalities. Also, the stability in the sense of Ulam–Hyers and Ulam–Hyers–Rassias are
studied. An illustrative example with graphical and numerical simulations is also proposed.

This paper aims to establish conditions for the existence, uniqueness and Ulam-Hyers
stability of solutions for a coupled system of pantograph problem with three sequential
fractional derivatives. Two results on the uniqueness and existence of solutions are proved
to utilize the Leray-Schauder and Banach fixed point theorems and positive contraction-type
inequalities. Also, the stability in the sense of Ulam-Hyers and Ulam-Hyers-Rassias are
studied. In organize to clarify our comes almost, some illustrative cases are in addition …