  Considered is the distribution of the crosscorrelation between $m$-sequences
of length $2^m-1$, where $m=2k$, and $m$-sequences of shorter length $2^k-1$.
New pairs of $m$-sequences with three-valued crosscorrelation are found and the
complete correlation distribution is determined. Finally, we conjecture that
there are no more cases with a three-valued crosscorrelation apart from the
ones proven here.
