An Upper Bound on the Size of Sidon Sets

A classical combinatorial number theory problem is to determine the maximum size of a Sidon set of (Formula presented.), where a subset of integers is Sidon if all its pairwise sums are different. For this entry point into the subject, combining two elementary proofs, we decrease the gap between the upper and lower bounds by 0.2% for infinitely many values of n. We show that the maximum size of a Sidon set of (Formula presented.) is at most (Formula presented.) for n sufficiently large.