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