  We call a (not necessarily planar) embedding of a graph $G$ in the plane
\emph{sequential} if its vertices lie in $\mathbb Z^2$ and the line segments
between adjacent vertices contain no interior integer points. In this note, we
prove (i) a graph $G$ has a sequential embedding if and only if $G$ is
4-colorable, and (ii) if $G$ is planar, then $G$ has a sequential planar
embedding.

Combinatorics