%I #6 Aug 22 2017 20:53:11
%S 0,0,1,6,9,56,51,258,380,1500,1611,12298,10245,57108,121721,346146,
%T 474489,3589534,3397143,21984804,41570773,142619388,186027579,
%U 1476414178,1694455320,8146633638,15690141155
%N Number of step cyclic shifted sequences using exactly 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.
%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 A056411(n)-3*A002729(n)+3.
%Y Cf. A056411.
%K nonn
%O 1,4
%A _Marks R. Nester_