MJaxEq
$
\newcommand{\Re}{\mathrm{Re}\,} \newcommand{\pFq}[5]{{}_{#1}\mathrm{F}_{#2} \left( \genfrac{}{}{0pt}{}{#3}{#4} \bigg| {#5} \right)}
$
blablabl\pFq32{\frac12, -\frac k2, -\frac k2}{1, 1}{4}.
W_3(k) &= \mathrm{Re} \, {}_{3}\mathrm{F}_{2}\left(\genfrac{}{}{0pt}{\frac{1}{2},-\frac{k}{2},-\frac{k}{2}}{\Pi}\right