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