Let (p n ) and (q n ) be any two non-negative real sequences, with R n := ∑ n k=0 p k q n−k ̸ = 0 (n ∈ ℕ). Let ∑ ∞ k=0 a k be a series of real or complex numbers with partial sums (s n ), and set t p,q n := 1 R n ∑ n k=0 p k q n−k s k for n ∈ ℕ. In this paper, we present the necessary and sufficient conditions under which the existence of the limit lim n→∞ s n = L follows from that of lim n→∞ t p,q n = L. These conditions are one-sided or two-sided if (s n ) is a sequence of real or complex numbers, respectively.
MSC 2010: 40G15, 41A36We define the following sets:A(n, t) := {q λ n −k − q n−k : k = 0, 1, 2, . . . , n, λ > 1}, B(n, t) := {q k−λ n − q n−k : k = 0, 1, 2, . . . , t n , 0 < λ < 1}, where λ n := [λn] denotes the integral part of λn.