\[
\boxed{
{\frac {{\rm d}^{2}}{{\rm d}{x}^{2}}}y \left( x \right) =-1/4\,{\frac { \left( 4\,v \left( v+1 \right)  \left( \sin \left( x \right)  \right) ^{2}- \left( \cos \left( x \right)  \right) ^{2}+2-4\,{n}^{2} \right) y \left( x \right) }{ \left( \sin \left( x \right)  \right) ^{2}}}=0}
\]