On a sumset problem for integers

Shan-Shan Du, Hui-Qin Cao, Zhi-Wei Sun

Let $A$ be a finite set of integers. We show that if $k$ is a prime power or a product of two distinct primes then $$|A+k\cdot A|\ge (k+1)|A|-\lceil k(k+2)/4\rceil$$ provided $|A|\…