proposition: Lemma FR_lucas2 n: FR (lucas n.*2.+3) = n.*2.+1.
proof: Proof. by rewrite FR_lucas1 doubleK. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat) mathcomp(seq path fintype div bigop binomial) mathcomp(prime finset ssralg ssrnum ssrint)