%I #7 Aug 22 2017 20:53:10
%S 0,0,3,21,39,288,309,1659,3102,14148,17157,136227,130995,790128,
%T 1791489,5427597,8047839,64467180,64486017,437324331,871627041,
%U 3136899816,4278115101,35355632943,42359479638
%N Number of step shifted (decimated) sequences using exactly three different symbols.
%C See A056371 for an explanation of step shifts.
%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 A056372(n)-3*A056371(n)+3.
%Y Cf. A056372.
%K nonn
%O 1,3
%A _Marks R. Nester_