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Tuesday, January 26, 2021

**Abstract:** A sequence ${a_1, a_2,\dots, a_k}$ of integers is called a $B_2$ sequence if all the sums $a_i + a_j$, $1 \leq i \leq j \leq k$, are different. Let $F_2(n)$ be the maximum number of elements that can be selected from the set ${1,2,\dots,n}$ so as to form a $B_2$ sequence. Among others we give a new elementary proof for the result of Erdos and Turan (1941) that $F_2(n)= \sqrt{n} + O(n^{1/4})$.

Tuesday, February 2, 2021

Tuesday, February 9, 2021

Tuesday, February 16, 2021

Tuesday, February 23, 2021