\[ \boxed { {\frac {{\rm d}^{3}}{{\rm d}{x}^{3}}}y \left ( x \right ) - \left ( 4\,n \left ( n+1 \right ) {\it WeierstrassP} \left ( x,{\it g2},{\it g3} \right ) +a \right ) {\frac {\rm d}{{\rm d}x}}y \left ( x \right ) -2\,n \left ( n+1 \right ) {\it WeierstrassPPrime} \left ( x,{\it g2},{\it g3} \right ) y \left ( x \right ) =0} \]
Mathematica: cpu = 0.018002 (sec), leaf count = 43 \[ \text {DSolve}\left [-y'(x) (a+4 n (n+1) \wp (x;\text {g2},\text {g3}))-2 n (n+1) y(x) \wp '(x;\text {g2},\text {g3})+y^{(3)}(x)=0,y(x),x\right ] \]
Maple: cpu = 0.297 (sec), leaf count = 41 \[ \left \{ y \left ( x \right ) = \left ( {\it DESol} \left ( \left \{ { \frac {{\rm d}^{2}}{{\rm d}{x}^{2}}}{\it \_Y} \left ( x \right ) + \left ( -{n}^{2}{\it WeierstrassP} \left ( x,{\it g2},{\it g3} \right ) -n{\it WeierstrassP} \left ( x,{\it g2},{\it g3} \right ) -{\frac {a}{4} } \right ) {\it \_Y} \left ( x \right ) \right \} , \left \{ {\it \_Y} \left ( x \right ) \right \} \right ) \right ) ^{2} \right \} \]