\[ \boxed { {\frac {{\rm d}^{2}}{{\rm d}{x}^{2}}}y \left ( x \right ) +a{\frac {\rm d}{{\rm d}x}}y \left ( x \right ) +b \left ( y \left ( x \right ) \right ) ^{n}+1/4\, \left ( {a}^{2}-1 \right ) y \left ( x \right ) =0} \]
Mathematica: cpu = 25.262208 (sec), leaf count = 34 \[ \text {DSolve}\left [\frac {1}{4} \left (a^2-1\right ) y(x)+a y'(x)+b y(x)^n+y''(x)=0,y(x),x\right ] \]
Maple: cpu = 0.889 (sec), leaf count = 63 \[ \left \{ y \left ( x \right ) ={\it ODESolStruc} \left ( {\it \_a},[ \left \{ \left ( {\frac {\rm d}{{\rm d}{\it \_a}}}{\it \_b} \left ( { \it \_a} \right ) \right ) {\it \_b} \left ( {\it \_a} \right ) +a{\it \_b} \left ( {\it \_a} \right ) +b{{\it \_a}}^{n}+{\frac {{\it \_a}\,{a} ^{2}}{4}}-{\frac {{\it \_a}}{4}}=0 \right \} , \left \{ {\it \_a}=y \left ( x \right ) ,{\it \_b} \left ( {\it \_a} \right ) ={\frac {\rm d}{ {\rm d}x}}y \left ( x \right ) \right \} , \left \{ x=\int \! \left ( { \it \_b} \left ( {\it \_a} \right ) \right ) ^{-1}\,{\rm d}{\it \_a}+{ \it \_C1},y \left ( x \right ) ={\it \_a} \right \} ] \right ) \right \} \]