%I #8 Jun 17 2015 04:06:20
%S 1,1,1,2,2,4,2,4,4,6,8,12,18
%N Maximal size of binary code of length n and asymmetric distance 4.
%H T. Etzion, <a href="http://dx.doi.org/10.1109/18.104336">New lower bounds for asymmetric and unidirectional codes</a>, IEEE Trans. Inform. Theory, 37 (1991), 1696-1705.
%H J. H. Weber, <a href="http://repository.tudelft.nl/view/ir/uuid:d26eccf3-bf97-4340-bb1d-c099c91d456d">Bounds and Constructions for Binary Block Codes Correcting Asymmetric or Unidirectional Errors</a>, Ph. D. Thesis, Tech. Univ. Delft, 1989.
%H J. H. Weber, C. de Vroedt and D. E. Boekee, <a href="http://dx.doi.org/10.1109/18.21262">Bounds and constructions for binary codes of length less than 24 and asymmetric distance less than 6</a>, IEEE Trans. Inform. Theory, 34 (1988), 1321-1332.
%Y Cf. A010101, A010238, A010336.
%K nonn,nice,hard
%O 1,4
%A _N. J. A. Sloane_, Apr 10 2000