An improved lower bound for finite additive 2-bases

A set of non-negative integers A is an additive 2-basis with range n, if its sumset A+A contains 0,1,…,n but not n+1. Explicit bases are known with arbitrarily large size |A|=k and n/k2≥2/7>0.2857. We present a more general construction and improve the lower bound to 85/294>0.2891.