%I #6 Aug 22 2017 20:53:11
%S 1,1,3,8,13,65,67,322,573,2495,2979,23294,22217,133081,300947,909050,
%T 1345633,10766559,10762819,72954582,145362861,523026545,713213955,
%U 5893685746,7060765719,35303760331
%N Number of primitive (aperiodic) step shifted (decimated) sequence structures using a maximum of three different symbols.
%C See A056371 for an explanation of step shifts. 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)*A056392(n/d) where d|n.
%Y Cf. A056382.
%K nonn
%O 1,3
%A _Marks R. Nester_