%I
%S 0,0,6,36,150,534,1806,5760,18144,55830,17100,6,518580,1569750,
%T 4732014,14250450,42844320,128746950,38661,5376,1160688606,3483582660,
%U 10454059938,31368305694,941180,13006,282378679920
%N Number of primitive (aperiodic) words of length n which contain exactly three different symbols.
%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)*A001117(n/d) where dn.
%Y Cf. A000244, A001117, A054718.
%K nonn
%O 1,3
%A _Marks R. Nester_
