You can do this, for example:
Export["test.dat", Table[t, {t, 1, 800, 50}], "Table"]
Or a table with two columns:
Export["test.dat", Table[{t, t^2}, {t, 1, 800, 50}], "Table"]
Or a 20x20 matrix:
Export["test.dat", Table[i+j, {i, 20}, {j, 20}], "Table"]