proposition: Lemma FR_lucas3 n: FR (lucas n.*2.+4) = n.*2.+1.
proof: Proof. by rewrite FR_lucas1 /= uphalf_double. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat) mathcomp(seq path fintype div bigop binomial) mathcomp(prime finset ssralg ssrnum ssrint)