\[ y(x) \left (a x^3+\nu ^2-1\right )+\left (1-\nu ^2\right ) x y'(x)+x^3 y^{(3)}(x)=0 \] ✓ Mathematica : cpu = 0.591846 (sec), leaf count = 143
DSolve[(-1 + nu^2 + a*x^3)*y[x] + (1 - nu^2)*x*Derivative[1][y][x] + x^3*Derivative[3][y][x] == 0,y[x],x]
\[\left \{\left \{y(x)\to c_2 3^{\nu -1} a^{\frac {1-\nu }{3}} x^{1-\nu } \, _0F_2\left (;1-\frac {2 \nu }{3},1-\frac {\nu }{3};-\frac {a x^3}{27}\right )+c_3 3^{-\nu -1} a^{\frac {\nu +1}{3}} x^{\nu +1} \, _0F_2\left (;\frac {\nu }{3}+1,\frac {2 \nu }{3}+1;-\frac {a x^3}{27}\right )+\frac {1}{3} \sqrt [3]{a} c_1 x \, _0F_2\left (;1-\frac {\nu }{3},\frac {\nu }{3}+1;-\frac {a x^3}{27}\right )\right \}\right \}\] ✓ Maple : cpu = 0.121 (sec), leaf count = 81
dsolve(x^3*diff(diff(diff(y(x),x),x),x)+(-nu^2+1)*x*diff(y(x),x)+(a*x^3+nu^2-1)*y(x)=0,y(x))
\[y \left (x \right ) = c_{1} x \hypergeom \left (\left [\right ], \left [-\frac {\nu }{3}+1, \frac {\nu }{3}+1\right ], -\frac {a \,x^{3}}{27}\right )+c_{2} x^{-\nu +1} \hypergeom \left (\left [\right ], \left [1-\frac {2 \nu }{3}, -\frac {\nu }{3}+1\right ], -\frac {a \,x^{3}}{27}\right )+c_{3} x^{\nu +1} \hypergeom \left (\left [\right ], \left [\frac {2 \nu }{3}+1, \frac {\nu }{3}+1\right ], -\frac {a \,x^{3}}{27}\right )\]