### Define a big matrix in Sage

Hi all,

I would like to define a big matrix E (130$\times$ 30) with entries ~~looks ~~being a list like ~~ ~~E[11,1] = [x, [1,-2]];

E[14,1] = [x, ~~[1,-1,-2,1]];~~

E[15,1] = [x, [1,-1,-1,-1]];
[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?