%I #6 Aug 22 2017 20:53:11
%S 0,1,2,4,5,16,13,42,49,133,107,600,351,1385,2164,4416,4115,22043,
%T 14601,67872,88360,209827,190745,1074534,839122,2796647,3730532,
%U 11275300,9587579,67193198,35792567
%N Number of primitive (aperiodic) step shifted (decimated) sequence structures using exactly two different symbols.
%C See A056371 for an explanation of step shifts. Permuting the symbols will not change the structure. Identical to A056401 for n>1.
%D M. R. Nester (1999). Mathematical investigations of some plant interaction designs. PhD Thesis. University of Queensland, Brisbane, Australia. [See A056391 for pdf file of Chap. 2]
%F A056401(n)-A000007(n-1).
%Y Cf. A056386.
%K nonn
%O 1,3
%A _Marks R. Nester_