The Schnirelmann density of a set of nonnegative integers is the greatest lower bound of the fractions 
where 
is the number of terms in the set 
.
Schnirelmann Density
See also
Mann's Theorem, Schnirelmann's TheoremExplore with Wolfram|Alpha
References
Khinchin, A. Y. "The Landau-Schnirelmann Hypothesis and Mann's Theorem." Ch. 2 in Three Pearls of Number Theory. New York: Dover, pp. 18-36, 1998.Referenced on Wolfram|Alpha
Schnirelmann DensityCite this as:
Weisstein, Eric W. "Schnirelmann Density." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/SchnirelmannDensity.html