Difference sets without squares
A sequence \(a_ 1,a_ 2,..\). of natural numbers is constructed so that no difference \(a_ i-a_ j\) is a square and the number of \(a_ i\) up to x is \(\geq x^{0.73}\), improving a result of \textit{A. Sárközy} [Ann. Univ. Sci. Budap. Rolando Eötvös, Sect. Math. 21, 45-53 (1978; Zbl 0413.10051)].
scientific article; zbMATH DE number 3879034