\[ y(x) \left (a \text {sn}(x|k)^2+b\right )+y''(x)=0 \] ✗ Mathematica : cpu = 1.3509 (sec), leaf count = 0 , could not solve
DSolve[(b + a*JacobiSN[x, k]^2)*y[x] + Derivative[2][y][x] == 0, y[x], x]
✓ Maple : cpu = 0.682 (sec), leaf count = 69
\[ \left \{ y \left ( x \right ) ={\it \_C1}\,{\it HeunG} \left ( {k}^{-2},{\frac {b}{4\,{k}^{2}}},-{\frac {n}{2}},{\frac {n}{2}}+{\frac {1}{2}},{\frac {1}{2}},{\frac {1}{2}}, \left ( {\it JacobiSN} \left ( x,k \right ) \right ) ^{2} \right ) +{\it \_C2}\,{\it HeunG} \left ( {k}^{-2},{\frac {{k}^{2}+b+1}{4\,{k}^{2}}},{\frac {n}{2}}+1,-{\frac {n}{2}}+{\frac {1}{2}},{\frac {3}{2}},{\frac {1}{2}}, \left ( {\it JacobiSN} \left ( x,k \right ) \right ) ^{2} \right ) {\it JacobiSN} \left ( x,k \right ) \right \} \]