\[
\boxed{
{\frac {{\rm d}^{3}}{{\rm d}{x}^{3}}}y \left( x \right) + \left( -{n}^{2}+1 \right) {\it WeierstrassP} \left( x,{\it g2},{\it g3} \right) {\frac {\rm d}{{\rm d}x}}y \left( x \right) +1/2\, \left(  \left( -{n}^{2}+1 \right) {\it WeierstrassPPrime} \left( x,{\it g2},{\it g3} \right) -a \right) y \left( x \right) =0}
\]