Jiraporn ReunsumritThanin Sitthiwirattham2025-03-102025-03-102020Mathematics2227739010.3390/math80404762-s2.0-85084438409https://repository.dusit.ac.th//handle/123456789/4763In this paper, we propose sequential fractional delta-nabla sum-difference equations with nonlocal fractional delta-nabla sum boundary conditions. The Banach contraction principle and the Schauder's fixed point theorem are used to prove the existence and uniqueness results of the problem. The different orders in one fractional delta differences, one fractional nabla differences, two fractional delta sum, and two fractional nabla sum are considered. Finally, we present an illustrative example. © 2020 by the authors.All Open Access; Gold Open AccessExistenceNonlocal fractional delta-nabla sum boundary value problemSequential fractional delta-nabla sum-difference equationsUniquenessArticleScopus