 Indecomposable modules of a cyclic p-group in characteristic p

Let $C_{p^n}=⟨g⟩$ and let $k$ have characteristic $p$. With $u=g-1$,Its finite-dimensional indecomposable modules areEach is a uniserial module, with radical $u{M}_r$ and one-dimensional socle $u^{r-1}{M}_r$.