\[ \boxed { {\frac {{\rm d}^{2}}{{\rm d}{x}^{2}}}y \left ( x \right ) =-1/4\,{\frac { \left ( -{x}^{2} \left ( {a}^{2}-1 \right ) +2\, \left ( a+3 \right ) bx-{b}^{2} \right ) y \left ( x \right ) }{{x}^{2}}}=0} \]
Mathematica: cpu = 0.033504 (sec), leaf count = 110 \[ \left \{\left \{y(x)\to c_1 M_{\frac {(a+3) b}{2 \sqrt {a^2-1}},\frac {\sqrt {b \left (b^2+1\right )}}{2 \sqrt {b}}}\left (\sqrt {a^2-1} x\right )+c_2 W_{\frac {(a+3) b}{2 \sqrt {a^2-1}},\frac {\sqrt {b \left (b^2+1\right )}}{2 \sqrt {b}}}\left (\sqrt {a^2-1} x\right )\right \}\right \} \]
Maple: cpu = 0.187 (sec), leaf count = 73 \[ \left \{ y \left ( x \right ) ={\it \_C1}\,{{\sl M}_{{\frac { \left ( a+3 \right ) b}{2}{\frac {1}{\sqrt {{a}^{2}-1}}}},\,{\frac {1}{2}\sqrt {{b }^{2}+1}}}\left (\sqrt {{a}^{2}-1}x\right )}+{\it \_C2}\,{{\sl W}_{{ \frac { \left ( a+3 \right ) b}{2}{\frac {1}{\sqrt {{a}^{2}-1}}}},\,{ \frac {1}{2}\sqrt {{b}^{2}+1}}}\left (\sqrt {{a}^{2}-1}x\right )} \right \} \]