to the risk of sounding redundant,
[tex]\bf \begin{array}{ccccccccc}
k=2&&k=3&&k=4&&k=5&&k=6\\\\
\frac{\underline{2}+2}{2(\underline{2})}&&\frac{\underline{3}+2}{2(\underline{3})}&&\frac{\underline{4}+2}{2(\underline{4})}&&\frac{\underline{5}+2}{2(\underline{5})}&&\frac{\underline{6}+2}{2(\underline{6})}\\\\
1&+&\cfrac{5}{6}&+&\cfrac{6}{8}&+&\cfrac{7}{10}&+&\cfrac{8}{12}
\end{array}[/tex]
and surely you'd know what that is.
