\[ y''(x)=\frac {18 y(x)}{(2 x+1)^2 \left (x^2+x+1\right )} \] ✓ Mathematica : cpu = 0.0705993 (sec), leaf count = 108
\[\left \{\left \{y(x)\to \frac {c_1 \left (x^2+x+1\right )}{(2 x+1)^2}+\frac {c_2 \left (16 x^3+24 x^2-12 \sqrt {3} x^2 \tan ^{-1}\left (\frac {2 x+1}{\sqrt {3}}\right )+30 x-12 \sqrt {3} x \tan ^{-1}\left (\frac {2 x+1}{\sqrt {3}}\right )-12 \sqrt {3} \tan ^{-1}\left (\frac {2 x+1}{\sqrt {3}}\right )+11\right )}{(2 x+1)^2}\right \}\right \}\] ✓ Maple : cpu = 0.075 (sec), leaf count = 58
\[ \left \{ y \left ( x \right ) ={\frac {1}{ \left ( 2\,x+1 \right ) ^{2}} \left ( -36\,{\it \_C2}\, \left ( {x}^{2}+x+1 \right ) \arctan \left ( 1/3\, \left ( 2\,x+1 \right ) \sqrt {3} \right ) +16\,{\it \_C2}\, \left ( {x}^{3}+{x}^{2}+{\frac {11\,x}{8}}+3/16 \right ) \sqrt {3}+{\it \_C1}\, \left ( {x}^{2}+x+1 \right ) \right ) } \right \} \]