Oscillation of solutions of some higher order linear differential equations

We shall assume that reader is familiar with the fundamental results and the standard notations of the Nevanlinna value distribution theory of meromorphic functions(see [11,14]). In addition, we will use the notation σ(f) to denote the order of growth of entire function f(z), σ2(f) to denote the hyper-order of f(z), λ(f)(λ2(f)) to denote the exponent(hyper-exponent) of convergence of the zero-sequence of f(z) and λ(f)(λ2(f)) to denote exponent(hyper-exponent) of convergence of distinct zero sequence of meromorphic function f(z). We also define