# .coefficients output

I am trying to solve a 2nd order differential eqn using power series. I used the .coeffients to get all the expressions with the constants a_0, a_1, a_2, a_3, .... The differential equation is homogenous so all of the expressions of coefficients = 0 and i want to work out how to get the expression and set it = 0 in a seperate list so i can put the list through solve() to find a_2, a_3, ... How can i do this?

Could you please provide your current code (in particular the differential equation) ?