Hello


I'm currently investigating the differential equation


$$f''=\left(\sum a\_n x^n\right)f$$


I was wondering if anyone could please provide me with a lead as to where I may find the Green's functions? Sadly I have not been able to achieve the result through my own computations



Green's Functions
This is indeed fairly standard. Using the two linearly independent solutions to your ODE that you already have you can just follow the procedure outlined e.g. [here](https://webspace.utexas.edu/dj955/www/notes/GreenFn.pdf) to construct the Green function. 


