1、使用hhline宏包\documentclass{article}\usepackage{hhline} % 双线表\begin{document}\begin{tabular}{r|r||r|r||r|r||r|r}\hline $n$&$I_n$&$n$&$I_n$&$n$&$I_n$&$n$&$I_n$\\\hhline{--||--||--||--} 19&0.008\ 3&14&0.011\ 2&9&0.016\ 9&4&0.034\ 3\\ 18&0.008\ 9&13&0.012\ 0&8&0.018\ 8&3&0.043\ 1\\ 17&0.009\ 3&12&0.013\ 0&7&0.021\ 2&2&0.058\ 0\\ 16&0.009\ 9&11&0.014\ 1&6&0.024\ 3&1&0.088\ 4\\ 15&0.010\ 5&10&0.015\ 4&5&0.028\ 5&0&0.182\ 3\\\hline\end{tabular}\end{document}
