“…The study of the existence of solutions for fractional differential equations is one of the most interesting and valuable topics [8,11,[18][19][20][21][22]. In recent contributions [18,19] one studied equations of the following form: where c D α 0,t is the Caputo fractional derivative of the order α ∈ (n -1, n), n ∈ N, f : J × R → R, J = [0, T] and I k : R → R and 0 = τ 0 < τ 1 < • • • < τ m < τ m+1 = T, and we let x(τ + k ) = lim ε→0 + x(τ k + ε) and x(τk ) = lim ε→0 -x(τ k + ε) represent the right and left limits of x(t) at t = τ k , respectively.…”