Define a big matrix in Sage
I would like to define a big matrix E (130$\times$ 30) with entries being a list like E[11,1] = [x, [1,-2]];
E[14,1] = [x, [1,-1,-2,1]]; or 0. These entries are stored in a separate file which is readable by Pari but not Sage.
How do I define it by Sage?