Cobham, A. "On the Base-Dependence of Sets of Numbers Recognizable by Finite Automata." Math. Systems Th.3, 186-192, 1969.Cobham, A. "Uniform Tag Sequences." Math. Systems Th.6, 164-192, 1972.Sloane, N. J. A. Sequence A048645 in "The On-Line Encyclopedia of Integer Sequences."