[tex]\bf \begin{array}{|ll|ll} \cline{1-2} term&value\\ \cline{1-2} a_1&3\\[0.8em] a_2&\stackrel{3\cdot 2}{6}\\[0.8em] a_3&\stackrel{6\cdot 2}{12}\\[0.8em] a_4&\stackrel{12\cdot 2}{24}\\[0.8em] a_5&\stackrel{24\cdot 2}{48}\\[0.8em] a_6&\stackrel{48\cdot 2}{96} \\ \cline{1-2} \end{array}[/tex]
