1-butanol, and so on. The single-ring cycloalkanes form another such series, starting with cyclopropane. Biopolymers also form homologous series, for example the polymers of glucose such as cellulose oligomers starting with cellobiose, or the series of amylose oligomers starting with maltose, which are sometimes called maltooligomers. Homooligopeptides, oligopeptides made up of repetitions of only one amino acid can also be studied as homologous series. Inorganic homologous series Homologous series are not unique to organic chemistry. Titanium, vanadium, and molybdenum oxides all form homologous series (e.g. VnO2n − 1 for 2 < n < 10), called Magnéli phases, as do the silanes, SinH2n + 2 (with n up to 8) that are analogous to the alkanes, CnH2n + 2. See also Ruddlesden-Popper phase References Organic chemistry Crystallography Inorganic chemistry