Hi Carlos,
If you have a function and want to evaluate it for several different values, map the function over a list of those values.
f1[n_] := n*n;
f1 /@ {1, 3, 6}
(* {1, 9, 36} *)
f2[n_] := RandomInteger[{-n, n}, {2, 2}]
f2 /@ {3, 5, 9}
(* {{{2, 1}, {-3, 0}}, {{1, 3}, {1, 0}}, {{-4, 4}, {-5, 0}}} *)