%I #6 Aug 22 2017 20:53:11
%S 0,0,0,3,12,136,204,1437,3520,20700,31956,317513,390364,2973536,
%T 8504720,32471391,61276740,622088400,790198476,6798297447,17290258088,
%U 79394956608,138325216092,1460955482487
%N Number of step cyclic shifted sequences using exactly four 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 A056412(n)-4*A056411(n)+6*A002729(n)-4.
%Y Cf. A056412.
%K nonn
%O 1,4
%A _Marks R. Nester_