%I #6 Aug 22 2017 20:53:11
%S 1,2,3,7,8,37,36,219,452,3000,5652,74961,126758,1371016,5653854,
%T 31440841,87796362,1319722484,2491714134,31893717065,121274777228,
%U 832622962686,2170594048582,34308978981089
%N Step cyclic shifted sequence structures using a maximum of six 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 Use de Bruijn's generalization of Polya's enumeration theorem as discussed in reference.
%Y Cf. A056414.
%K nonn
%O 1,2
%A _Marks R. Nester_