  As proved by Hedden and Ording, there exist knots for which the Ozsvath-Szabo
and Rasmussen smooth concordance invariants, tau and s, differ. The
Hedden-Ording examples have nontrivial Alexander polynomials and are not
topologically slice. It is shown in this note that a simple manipulation of the
Hedden-Ording examples yields a topologically slice Alexander polynomial one
knot for which tau and s differ. Manolescu and Owens have previously found a
concordance invariant that is independent of both tau and s on knots of
polynomial one, and as a consequence have shown that the smooth concordance
group of topologically slice knots contains a summand isomorphic to a free
abelian group on two generators. It thus follows quickly from the observation
in this note that this concordance group contains a subgroup isomorphic to a
free abelian group on three generators.
