若函数\(\textit{f}\)：\(\textbf{N}\rightarrow\textbf{N}\)同时满足以下条件：\((1)\) 函数\(\textit{f}\)严格单调递增；\((2)\)对任意\(m\)，\(n\in\textbf{N}\)， \(\textit{f}(mn)=\textit{f}(m)\cdot\textit{f}(n)\)；\((3)\textit{f}(2)=4. \;\;\)则\(\textit{f}(1)+\textit{f}(3)=\underline{\qquad \blacktriangle\qquad }\)
原文：https://www.cnblogs.com/xuebajunlutiji/p/11727519.html