How to write a symbolic expression to an array

I am trying to write a function to calculate the normalisation factors for the first n_max eigen-functions of an eigen-problem. I want the function output, unperturbed_eig, to be a list of the normalisation factors, partition(k), which I have already calculated, multiplied by the eigenfunctions themselves. The eigenfunctions are symbolic expressions dependent on k, which is the eigenfunction number, and change if k is odd or even. The eigenfunctions are also dependent on x which I want to remain as a symbolic variable. However, I am struggling to create a list of the eigenfunctions and their normalisation factors when I have to evaluate k and keep x as symbolic. So far I have:

if true
  % code
normalised_eig=zeros(n_max,1);
syms x
for k=1:n_max
  if mod(k,2)==1
      normalised_eig(k)=double((1/partition(k))*cos(k*pi*x/a));
  else
      normalised_eig(k)=double((1/partition(k))*sin(k*pi*x/a));
  end
end
clear x
unperturbed_eig=normalised_eig;
end

I've also tried using the fprintf and sprintf but to no avail. How can I do this?