sentences:  The Erdős–Tetali theorem states that, for every formula_2, there exists an additive basis of order formula_2 whose number of representations of each formula_16 is formula_22.A theorem of Lev Schnirelmann states that any sequence with positive Schnirelmann density is an additive basis.This follows from a stronger theorem of Henry Mann according to which the Schnirelmann density of a sum of two sequences is at least the sum of their Schnirelmann densities, unless their sum consists of all natural numbers.