<p style='text-indent:20px;'>This paper deals with the following nonlinear fractional equation with an external source term</p><p style='text-indent:20px;'><disp-formula> <label/> <tex-math id="FE1"> \begin{document}$ \begin{equation*} \label{eqS0.1} (-\Delta)^{s}u +u = K(x)u^{p}+f(x), \; u&gt;0, \; x\in{\Bbb R}^N, \end{equation*} $\end{document} </tex-math></disp-formula></p><p style='text-indent:20px;'>where <inline-formula><tex-math id="M1">\begin{document}$ N&gt;2s $\end{document}</tex-math></inline-fo...