By counting the coset leaders for cosets of weight 3 of the Melas code we give a new proof for the characterization of Kloosterman sums divisible by 3 for F2m where m is odd. New results due to Charpin, Helleseth and Zinoviev then provide a connection to a characterization of all a in F2m such that Tr(a1/3)=0; we prove a generalization to the case Tr(a1/(2k-1))=0. We present an application to constructing caps in PG(n,2) with many free pairs of points.