fact: Definition harmonic_mean (R : numDomainType) (u_ : R ^nat) : R ^nat := let v := [sequence (u_ n)^-1]_n in [sequence (n.+1%:R / series v n.+1)]_n.
imports: mathcomp(all_ssreflect ssralg ssrint ssrnum matrix) mathcomp(interval rat) mathcomp(mathcomp_extra boolp classical_sets functions) mathcomp(set_interval) reals ereal signed topology normedtype landau