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%I #6 Aug 22 2017 20:53:11
%S 1,1,1,2,2,5,4,10,9,22,14,78,36,124,180,343,260,1329,804,3732,4428,
%T 9742,8384,47364,33778,108292,138756,408244,331184,2251604,1155734
%N Number of primitive (period n) step cyclic shifted sequence structures using a maximum of two different symbols.
%C See A056371 for an explanation of step shifts. Under step cyclic shifts, abcde, bdace, bcdea, cdeab and daceb etc. are equivalent. Permuting the symbols will not change the structure.
%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 Sum mu(d)*A056429(n/d) where d divides n.
%Y Cf. A002730.
%K nonn
%O 1,4
%A _Marks R. Nester_