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%I #6 Aug 22 2017 20:53:11
%S 1,1,2,4,5,18,15,60,80,293,295,2217,1777,9763,20632,58362,79553,
%T 600696,567543,3671674,6935728,23785615,31017007,246154210,282456327,
%U 1357925621,2615206650,11358502734
%N Number of primitive (period n) step cyclic shifted sequence structures using a maximum of three 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)*A056430(n/d) where d divides n.
%Y Cf. A056420.
%K nonn
%O 1,3
%A _Marks R. Nester_