It is known that all solutions of the difference equation Δx(n)+p(n)x(n−k)=0,n≥0, where {p(n)}∞n=0 is a nonnegative sequence of reals and k is a natural number, oscillate if lim infn→∞∑n−1i=n−kp(i)>(kk+1)k+1. In the ...