Three solutions for a fractional Schrödinger equation with vanishing potentials

In this paper, we study the following fractional Schrödinger equation (−Δ)su+V(x)u=K(x)f(u)+λW(x)|u|p−2u,x∈RN,where λ>0 is a parameter, (−Δ)s denotes the fractional Laplacian of order s∈(0,1), N>2s, W∈L22−p(RN,R+), 1