  It is shown that the gentle one-cycle algebra $\Lambda(n-1,1,1)$ has Hall
polynomials. The Hall polynomials are explicitly given for all triples of
indecomposable modules, and as a consequence, the Ringel--Hall Lie algebra of
$\Lambda(n-1,1,1)$ is shown to be isomorphic to its Riedtmann Lie algebra.
