  We reprove twice, in a simpler but as elementary way, a result by Hor\'ak and
Skula (1985) who determined, among all sequences of integers defined by
$$u_1=1,\quad u_2=R,\quad u_{n+2}=Pu_{n+1}-Qu_n$$ for some integers $P,Q,R$,
those which satisfy the strong divisibility condition $$\forall i,j\in\mathbb
N^*\quad u_i\land u_j=\left|u_{i\land j}\right|,$$ where $\land$ denotes the
greatest common divisor.
