Selecting the main chain of an alkane as the path that yields the least complex side chains without themaximum-length constraint leads to an efficient generating algorithm representable as nested binary trees.The largest side chain required to specify an N-carbon alkane becomes (N-1)/3. This allows 3.8 millionC1−C22 alkanes to be coded for name translation in dictionary order, using an alphabet of 33 C1−C6 alkylgroups also ranked by complexity. The generating process produces reversible isomer codes already incanonical order, making the computation rate in isomers per second inverse linear with N and much fasterthan reported rates for other structure generators.