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